Surgical management of ovarian endometrioma in a patient with fibrodysplasia ossificans progressiva: a case report

A 27-year-old Asian female presented with a chief complaint of an ovarian cyst identified during an examination conducted over the past two weeks. She reported a history of irregular menstruation, characterized by menstrual periods lasting 3 to 6 days, accompanied by scanty menstruation and dysmenorrhea. Recent pelvic B-ultrasound at a local hospital for dysmenorrhea, revealed a mass in the left adnexal region and pelvic effusion. No intermenstrual or postcoital bleeding was reported, dyspareunia, or bowel/bladder dysfunction was reported. The patient was clinically diagnosed with FOP at age 5 based on progressive heterotopic ossification and typical clinical manifestations (including congenital big toe deformity). Physical examination revealed temperature 36.5 °C, pulse 85, BP 123/86 and the patient exhibited signs of stunted development and malnutrition, temporomandibular joint involvement, resulting in limited mouth opening, only about 1.5 finger widths. In addition, there was chest wall stiffness and restricted chest expansion. Abdominal examination revealed a nontender, poorly defined mass in the lower abdomen, but due to severe skeletal deformity and patient positioning, it was difficult to determine the nature of the mass. All joints were affected (cervical spine, temporomandibular joint, multiple joints in the limbs), with complete restriction of limb movement; the lower limbs could not be placed flat, and independent walking was impossible. Cervical spine: Completely ankylosing, with no flexion, extension or rotational range of motion. Hard, fixed ossified masses were palpable in the soft tissues of the limbs. Examination of the musculoskeletal system revealed chest wall stiffness; breathing was primarily mediated by diaphragmatic movement, with minimal chest wall movement. Neurological examination revealed the presence of superficial sensation, symmetrical deep tendon reflexes, and no focal neurological deficits. The upper body can lie flat, and bowel function was controlled. The patient's condition was currently stable. She had undergone "partial bone resection" 16 years prior (specific details unknown). The patient denies any history of trauma or chronic systemic diseases. Menarche occurred at the age of 18. The patient was unmarried and nulliparous, with no history of gynecological surgery. She had been residing in the local area for an extended period and reported no habits of smoking or alcohol consumption. She denied any family history of genetic disorders, as well as any personal history of hepatitis, tuberculosis, malaria, hypertension, heart disease, diabetes, cerebrovascular disease, or mental illness. Additionally, there was no reported history of allergies to food or medications. Bilateral big toe deformity (hallux valgus, short toe), which is a typical congenital feature of FOP. Assistance was required for her admission to the ward. Due to the patient's fixed skeletal deformities, joint contractures, and inability to assume the standard lithotomy position, routine speculum and bimanual examinations could not be performed. We have made a timeline of key diagnosis and treatment-related events for patients (see Fig.  1 ). Fig. 1 Timeline of patient's disease progression Timeline of patient's disease progression The HLA-B27 nucleic acid test result was negative. C-reactive protein (CRP) was normal, infectious disease examination was normal, antinuclear antibodies and immunoglobulins were basically normal, and tumor markers were significantly elevated: CA125 (351.52 U/mL, reference value 0–30.2) and CA19-9 (386.79 U/mL, reference value 0–37), indicating the need to exclude the risk of gynecological or digestive tract tumors; coagulation abnormalities: D-dimer increased (1.42 μg/mL, reference value 0–0.50), indicating thrombosis or hyperfibrinolysis; blood indicators continued to be abnormal: thrombocytopenia (98 → 103 × 10⁹/L, reference value 125–350); mean hemoglobin concentration decreased (MCHC 305–313 g/L, reference value 316–354); bilirubin was slightly elevated: total bilirubin 24.19 μmol/L (reference value 0–23), direct bilirubin 5.22 μmol/L (reference value 0–4); others: positive fecal occult blood + loose stools, indicating gastrointestinal abnormalities; complement C3 critical decrease (0.91 g/L, reference value 0.90–1.80). Ultrasound examination: The combined use of ultrasound and CT can improve the accuracy of diagnosing pelvic diseases [ 16 ]. Pelvic ultrasound conducted on May 9, 2025 (see Fig.  2 ), revealed an anteriorly positioned uterus of normal dimensions, accompanied by a cervical cyst measuring 17 × 14 mm, which exhibited anechoic characteristics. In addition, a cystic mass measuring 103 × 67 × 96 mm was identified in the left adnexal region, characterized by separated light bands and dense light spots within, as well as poor sound transmission, rendering the left ovary indistinct. No masses were detected in the right adnexal area. The abdominal and pelvic cavities appeared free of abnormalities, with no echogenic findings, measuring 29 mm in depth for the abdominal cavity and 45 × 24 mm for the pelvic cavity. These findings suggest the presence of a cystic mass in the left adnexal area, potentially indicative of a cystadenoma or an ovarian endometriotic cyst. Furthermore, an echocardiogram performed on May 12, 2025 (see Fig.  3 ), demonstrated normal atrioventricular dimensions, with a short posterior leaflet of the mitral valve exhibiting mild regurgitation, alongside mild tricuspid valve regurgitation. The right ventricular pressure was estimated at 30 mmHg, consistent with a Doppler cardiogram within normal parameters. Fig. 2 Pelvic ultrasound. A Pelvic fluid accumulation (arrow); B Ovarian cyst (arrow) Fig. 3 Echocardiogram Pelvic ultrasound. A Pelvic fluid accumulation (arrow); B Ovarian cyst (arrow) Echocardiogram CT examination: CT is of great value in the evaluation of spinal diseases and in combination with ultrasound in the evaluation of pelvic diseases [ 16 , 17 ]. A plain scan of the neck on May 12, 2025, revealed a straightening of the physiological curvature of the cervical spine, abnormal morphology, and fusion of the vertebral margins (see Fig.  4 ), suggesting multiple morphological alterations in the cervical spine. The possibility of ankylosing spondylitis was considered. A plain chest scan on May 8, 2025, identified nodules in the middle and lower lobes of the right lung, measuring 5.8 mm in diameter, along with increased pulmonary texture, thoracic spine scoliosis, and the formation of multiple bone bridges between the shoulders and ribs bilaterally. A plain scan of the thoracic spine on May 12, 2025 (see Fig.  5 ), confirmed scoliosis and uneven density in some vertebrae. Additionally, a plain scan of the lumbar spine on May 14, 2025 (see Fig.  6 ), indicated lumbar spine scoliosis, bamboo-like changes in the vertebrae characterized by partial density reduction and marginal hyperplasia, dilation of the L3-4 spinal canal, and cystic low-density lesions in the pelvic cavity, with ankylosing spondylitis again considered as a differential diagnosis. Fig. 4 Neck CT. A Fusion of vertebral margins (arrow); B Multiple morphological changes in the cervical spine (arrow) Fig. 5 Chest CT. Uneven density in the thoracic vertebrae (arrow) Fig. 6 Waist CT. Vertebral canal dilation (arrow) Neck CT. A Fusion of vertebral margins (arrow); B Multiple morphological changes in the cervical spine (arrow) Chest CT. Uneven density in the thoracic vertebrae (arrow) Waist CT. Vertebral canal dilation (arrow) X-ray examination: Radiographic evaluation of the cervical spine, conducted on May 12, 2025 (see Fig.  7 ), revealed a loss of the normal cervical lordosis, with the vertebral bodies exhibiting a bamboo-like appearance accompanied by marginal osteophyte formation. Additionally, the facet joints appeared indistinct. These findings suggest morphological alterations of the cervical spine, warranting consideration of ankylosing spondylitis in the differential diagnosis. Fig. 7 Chest X-ray. A Vertebral bodies exhibit bamboo-like changes; B Thoracic scoliosis deformity (arrow) Chest X-ray. A Vertebral bodies exhibit bamboo-like changes; B Thoracic scoliosis deformity (arrow) Electrocardiogram (ECG) showed sinus rhythm and normal electrocardiogram (see Fig.  8 ). Fig. 8 Electrocardiogram Electrocardiogram 1. Ovarian endometrioma: The patient presented with symptoms of dysmenorrhea, irregular menstruation (with cycles ranging from 3 to 12 days), and oligomenorrhea. Imaging studies, including B-ultrasound conducted at both an external facility and our institution, revealed a cystic mass in the left adnexal region measuring 69 × 85 mm initially, which later increased to 103 × 67 × 96 mm. The mass contained septations and dense echogenic foci, exhibited poor sound transmission, and was associated with pelvic effusion. CT imaging identified a cystic low-density lesion within the pelvic cavity. 2. Fibrodysplasia ossificans progressiva (FOP): The onset of FOP symptoms occurred at the age of 5, with progressive deterioration affecting the cervical spine (resulting in ankylosis and an inability to flex), temporomandibular joint (limiting mouth opening to 1.5 transverse fingers), and multiple other joints throughout the body, leading to complete restriction of movement. Imaging studies, including X-ray and CT scans, demonstrated fusion and bamboo-like changes in the cervical spine, scoliosis of the thoracolumbar spine, and multiple bone bridges between the shoulder and ribs. Although imaging reports initially suggested the exclusion of ankylosing spondylitis, the combination of the patient's distinctive medical history and extensive heterotopic ossification was consistent with the characteristics of FOP. Finally, the patient had a history of previous surgery: "partial bone resection" 16 years ago. 1. Ovarian endometrioma: The patient presented with symptoms of dysmenorrhea, irregular menstruation (with cycles ranging from 3 to 12 days), and oligomenorrhea. Imaging studies, including B-ultrasound conducted at both an external facility and our institution, revealed a cystic mass in the left adnexal region measuring 69 × 85 mm initially, which later increased to 103 × 67 × 96 mm. The mass contained septations and dense echogenic foci, exhibited poor sound transmission, and was associated with pelvic effusion. CT imaging identified a cystic low-density lesion within the pelvic cavity. 2. Fibrodysplasia ossificans progressiva (FOP): The onset of FOP symptoms occurred at the age of 5, with progressive deterioration affecting the cervical spine (resulting in ankylosis and an inability to flex), temporomandibular joint (limiting mouth opening to 1.5 transverse fingers), and multiple other joints throughout the body, leading to complete restriction of movement. Imaging studies, including X-ray and CT scans, demonstrated fusion and bamboo-like changes in the cervical spine, scoliosis of the thoracolumbar spine, and multiple bone bridges between the shoulder and ribs. Although imaging reports initially suggested the exclusion of ankylosing spondylitis, the combination of the patient's distinctive medical history and extensive heterotopic ossification was consistent with the characteristics of FOP. Finally, the patient had a history of previous surgery: "partial bone resection" 16 years ago. Differential diagnosis: Age of Onset: FOP typically begins in early childhood (5 years old in this case), although ankylosing spondylitis (AS) is more common in young adults. Characteristic Deformity: A congenital big toe deformity is present, which is not present in AS. Heterotopic Ossification Pattern: Ossification in FOP mainly occurs in soft tissues (muscles, fascia), forming "ossified masses," although in AS, inflammation at the attachment points of ligaments and tendons leads to "ligamentous osteophytes" and joint fusion. Serological Markers: This patient was HLA-B27 negative, which is relatively rare in AS but irrelevant to the diagnosis of FOP. Past Surgical History: The patient had a history of "partial osteotomy" 16 years ago, consistent with the disease behavior of FOP-induced ossification following trauma. Preoperative preparation: Preoperative laboratory tests revealed elevated D-dimer and thrombocytopenia. Therefore, we performed bilateral lower extremity venous ultrasound, which did not detect deep vein thrombosis. Considering the patient's extremely limited mobility, the planned surgery, and the potential hypercoagulable state of the FOP (Follicular Unit Extraction) procedure, we implemented an aggressive VTE prevention strategy. Intermittent pneumatic compression was continuously used intraoperatively and postoperatively. Starting 6 h postoperatively, after confirming the absence of active bleeding, prophylactic doses of low molecular weight heparin (enoxaparin 40 mg, subcutaneously, once daily) were initiated until the patient's discharge. Meanwhile, based on the patient's unique body shape, we pre-designed a special surgical mattress and positioning pad using 3D scanning and printing technology. When positioning the patient for surgery, gel pads were placed on all bony prominences such as the sacrum, coccyx, scapula, and heels to ensure even pressure distribution and to strictly avoid improper traction or twisting of the limbs during the operation. This was aimed at minimizing the risk of soft tissue trauma and pressure injury, thereby reducing the risk of acute FOP (Follicular Occurrence). Preoperative preparation involved comprehensive laboratory testing, including routine hematological assessments, evaluation of hepatic and renal function, coagulation profiles, and immune markers such as antinuclear antibodies and HLA-B27 gene analysis. Additionally, tumor markers were evaluated. Comprehensive imaging studies of the entire body, encompassing the cervical, thoracic, and pelvic regions, were conducted to rule out any contraindications for surgery. Following the confirmation of the initial diagnosis, a multidisciplinary consultation was convened. To prevent acute FOP exacerbations that may be induced by surgical trauma, high-dose corticosteroids or other anti-inflammatory drugs were not routinely used perioperatively for prophylaxis, as there is currently a lack of high-level evidence to support their effectiveness and safety in such nonemergency surgeries, and there are concerns about the potential increase in infection risk. The core of the team's decision was to optimize minimally invasive surgical procedures and provide meticulous perioperative care to minimize traumatic stimulation at the source. Anesthesiology assessment: Preoperative anesthesia contraindications were ruled out. The patient reported difficulty in mouth opening, necessitating an evaluation for a potentially difficult airway. Provisions for an emergency tracheotomy were made, with the Ear-nose-throat (ENT) department on standby for assistance. ENT department assessment: In the event of challenges with oral intubation, nasal intubation was recommended, with preparations for tracheotomy support as a contingency. Critical care assessment: The patient was identified as high-risk during the perioperative period, warranting transfer to the ICU for postoperative monitoring. Nutrition department opinion: The patient was evaluated to be poorly nutritious and a reasonable enteral nutrition plan was required after surgery. At the same time, 3D printed special insoles, walker handrails, and surgical mattresses were made for special auxiliary equipment surgery, which helped the patient's surgery go smoothly. Special care: Oral care was changed to a confinement toothbrush to avoid injury. Anesthesiology assessment: Preoperative anesthesia contraindications were ruled out. The patient reported difficulty in mouth opening, necessitating an evaluation for a potentially difficult airway. Provisions for an emergency tracheotomy were made, with the Ear-nose-throat (ENT) department on standby for assistance. ENT department assessment: In the event of challenges with oral intubation, nasal intubation was recommended, with preparations for tracheotomy support as a contingency. Critical care assessment: The patient was identified as high-risk during the perioperative period, warranting transfer to the ICU for postoperative monitoring. Nutrition department opinion: The patient was evaluated to be poorly nutritious and a reasonable enteral nutrition plan was required after surgery. At the same time, 3D printed special insoles, walker handrails, and surgical mattresses were made for special auxiliary equipment surgery, which helped the patient's surgery go smoothly. Special care: Oral care was changed to a confinement toothbrush to avoid injury. Surgical procedure: On May 15, 2025, the patient underwent a transabdominal left adnexectomy combined with pelvic adhesion lysis under general anesthesia, with the procedure lasting from 09:05 to 09:50, totaling 45 min. Anesthesia and Airway Management: Given the patient's cervical spine stiffness and limited mouth opening (approximately 1.5 finger widths), the anesthesia team opted for a fiberoptic bronchoscopic-guided nasal awake endotracheal intubation protocol to avoid neck hyperextension and ensure airway safety. Preoperatively, an appropriate dose of glycopyrronium bromide was administered to reduce airway secretions, and lidocaine was used for topical anesthesia of the nasal cavity and pharynx. Under mild sedation (dexmedetomidine), the endotracheal tube was successfully inserted. Intraoperative combined intravenous and inhalation anesthesia was used, and nasotracheal intubation was successful. The procedure proceeded smoothly. The anesthesia record shows stable vital signs and no abnormalities in airway pressure. Throughout the procedure, the patient's vital signs remained stable, and no adverse events such as bleeding, laryngospasm, or hypoxemia occurred. Anesthesia induction and maintenance were performed using propofol, remifentanil, and cisatracurium. The surgical procedure was executed as follows: A longitudinal incision was made in the lower abdomen, revealing a cystic and enlarged left ovary, measuring 9 cm in diameter, which was densely adhered to the pelvic wall. We use Metzenbaum scissors for precise, sharp dissection, completely avoiding blunt dissection. During the separation of adhesions, the cyst ruptured, releasing a chocolate-like fluid, indicative of an endometriotic cyst. The ovarian suspensory ligament and fallopian tube isthmus were individually electrocoagulated and severed using bipolar electrocoagulation (Valleylab Force FX™). The left ovarian suspensory ligament was carefully dissected, ensuring the ureter was not compromised. The ligament and the isthmus of the fallopian tube were coagulated, and the left adnexa were excised. The excised specimen was subjected to intraoperative frozen section analysis, which indicated a benign cyst, likely of endometriotic origin. The pelvic cavity was irrigated, and the abdomen was closed upon confirmation of hemostasis. Intraoperative observations noted that the uterus was slightly enlarged, maintained a regular shape, and exhibited a smooth serosal surface. The left ovary was enlarged and about 9 cm in diameter, densely adhered to the side pelvic wall, the right adnexa and the left fallopian tube appeared normal in appearance, and a small amount of light bloody fluid was present in the pelvic cavity. The amount of bleeding during the operation was 5 ml. Intraoperative blood loss was estimated at approximately 5 ml. This extremely low blood loss was achieved through meticulous sharp adhesion separation and immediate, precise bipolar electrocoagulation of all bleeding points, avoiding extensive blunt dissection and tissue trauma. It should be noted that this estimate may not fully account for gauze smearing and evaporation, but it does reflect the very limited overall intraoperative bleeding. Throughout the procedure, the surgical team followed the principle of “no contact” or minimal contact in handling the tissue, moving gently and avoiding any form of traction, compression, or contusion of the soft tissue, aiming to minimize surgical trauma. Postoperative treatment: Following resuscitation in the recovery room, the patient was promptly transferred to the ICU for continuous monitoring, oxygen supplementation, and ECG surveillance. Postoperatively, the patient underwent active rehydration to maintain fluid homeostasis, and ceftriaxone sodium (1 g every 12 h, administered via intravenous infusion) was prescribed for antimicrobial prophylaxis. Concurrently, perineal care was administered to prevent urinary tract infections. The patient's diet was progressively advanced from liquid to semi-liquid, and ultimately to a high-protein general diet. Hematological parameters were closely monitored postoperatively. The surgical dressing was changed on the second postoperative day, and the incision/nail site demonstrated healing. Pathological results: Intraoperative frozen display (2025–05-15): (left appendage) benign cyst, tending to endometriosis cyst. The final paraffin pathological results: consistent with endometriosis cyst, chronic fallopian tube inflammation. Postoperative recovery and discharge: On the first postoperative day, the patient did not experience flatus, but continued with rehydration and anti-inflammatory treatment. By the second postoperative day, the patient passed flatus, and electrocardiogram monitoring was discontinued following the initiation of a liquid diet. Bowel movements resumed on the third postoperative day. By the fifth postoperative day, the surgical incision had healed well, with no reported pain or discomfort, and the patient was prepared for discharge. Postoperative complete blood count revealed a platelet count of 103 × 10 9 /L, a white blood cell counts of 6.57 × 10 9 /L, and a neutrophil percentage of 65.4%, all within normal limits. At the time of discharge, the patient exhibited a normal body temperature, a soft abdomen without tenderness, and a well-healed incision classified as II/N. To reduce the risk of heterotopic ossification induced by surgical trauma, in accordance with the FOP management guidelines, patients were given high-dose glucocorticoid (methylprednisolone) pulse therapy starting 24 h before surgery, and the dose was gradually reduced after surgery according to their condition. The patient was discharged on the 5th postoperative day. The incision healed well with no signs of infection. The patient returned for a follow-up examination 30 days postoperatively. The patient reported no significant abdominal pain or new joint pain, and the incision healing was grade II/N. Pelvic ultrasound examination did not reveal pelvic effusion, new cysts, or significant new ectopic ossifications. Laboratory tests showed that CA125 levels decreased to 42.1 U/mL, CA19-9 decreased to 58.3 U/mL, and the platelet count recovered to 135 × 10⁹/L. A telephone follow-up was conducted 90 days postoperatively. The patient reported being largely able to manage daily life without worsening of activity limitations or new joint stiffness. The visual analog scale (VAS) score for pain was 1 (out of 0–10), and no analgesics were used. Although mobility was still limited due to underlying medical conditions, no acute exacerbations of FOP induced by surgery occurred. Short-term follow-up did not reveal any surgery-induced acute exacerbation of FOP. Long-term monitoring plan: We recommend that patients undergo pelvic ultrasound and tumor marker monitoring every 6 months, and a whole-body skeletal imaging evaluation (such as low-dose CT or X-ray) annually to detect and manage possible heterotopic ossification or cyst recurrence early. We also advise patients to seek medical attention promptly if any new joint swelling, pain, or limited mobility occurs.

This report of FOP concomitant with ovarian endometriosis cysts emphasizes the critical value of multidisciplinary collaboration and tailored surgical strategies in managing extremely rare comorbidities, setting a precedent for technical innovation in complex pelvic surgeries.

FOP is a rare autosomal dominant genetic disorder characterized by progressive soft tissue heterotopic ossification occurring spontaneously or after minor trauma. Consequently, surgical interventions or trauma can exacerbate ossification and worsen the condition. Historically, FOP has been regarded as a relative contraindication to surgical procedures. Ovarian endometriomas, common in reproductive-age women, are primarily associated with symptoms such as dysmenorrhea, infertility, and pelvic adhesions, with surgical intervention often serving as a definitive treatment [ 6 , 18 ]. The concurrence of FOP and ovarian endometriomas presents an exceptionally rare clinical scenario. To date, this is the first case reported with such a combination. The diagnosis of FOP in this case is based on its characteristic clinical phenotype and imaging findings. Although genetic testing (ACVR1 mutation analysis) is the gold standard for diagnosis, it was not performed due to limitations. However, the onset in childhood, progressive heterotopic ossification, and characteristic big toe deformity constitute sufficient evidence for a clinical diagnosis of FOP. The work in the surgical preparation process was reviewed, such as multidisciplinary consultation, selection of catheter insertion method, etc. In this article, we report in detail the patient's age, symptoms, cyst size, degree of pelvic wall adhesion, FOP involvement, surgical method, anesthesia, and corresponding technical assistance. However, the differences in the specific conditions of FOP in this report allow this article to add more clinical experience to practitioners in this field. It should be noted that the purpose of this surgery was to remove symptomatic ovarian endometriotic cysts, not to treat FOP-related ectopic ossification. The pelvic ectopic ossification observed intraoperatively was considered a chronic, stable manifestation of FOP. Due to the extreme risk of inducing new ectopic ossification, we did not perform biopsies or excisions of any ectopic ossification tissue. Therefore, the submitted specimens were limited to the left adnexa, and the pathological examination focused on gynecological diagnosis, without microscopic confirmation of ectopic ossification, consistent with the treatment objectives of this surgery. Furthermore, the short-term follow-up results of this case showed that through meticulous surgery and multidisciplinary collaboration, rapid recovery after gynecological surgery can be achieved in patients with FOP without inducing early heterotopic ossification. However, the disease progression of FOP is long-term and progressive; therefore, systematic long-term follow-up and individualized monitoring programs remain crucial for managing these patients. The diagnosis in this case presents greater complexity compared to the previous instance. Differentiating heterotopic ossification of the pelvis in patients with FOP from bone tumors is challenging, although distinguishing ovarian cysts from inflammatory masses and tumors also poses difficulties. The patient's preoperative CT showed "pelvic cystic low-density lesions”， but concurrent ossification complicated imaging interpretation. Imaging results indicate that ankylosing spondylitis can be excluded, thus emphasizing the necessity for clinicians to integrate comprehensive examination results with the patient's physical examination. It is imperative to thoroughly assess the patient's medical history and develop an appropriate surgical plan accordingly. The complexity of surgical procedures for patients with FOP is anticipated to escalate, with a concomitant likelihood of exacerbating FOP symptoms postoperatively, potentially resulting in a range of complications. Primarily, the altered anatomical structures in FOP patients present significant surgical challenges. Cervical ankylosis may impede tracheal intubation during anesthesia, although pelvic ossification can influence the selection of surgical positioning, thereby affecting the visibility and accessibility of the surgical field. A multidisciplinary consultation was conducted before the operation, involving anesthesiology and otolaryngology, who worked together to develop an airway management plan. Malnutrition was addressed in the Dietetics Unit and the Intensive Care Medicine Unit assessed the need for postoperative ICU monitoring. Customized surgical mattresses were prepared in advance to optimize patient positioning for the procedure. The surgery itself is fraught with challenges, as FOP patients are predisposed to increased bleeding due to the heightened fragility of muscle tissue. We employ precise separation of adhesions to minimize blunt dissection, concurrently applying bipolar electrocoagulation to control hemostasis and prevent excessive intraoperative bleeding. Due to the inability to utilize a laparoscopic approach in cases of joint ankylosis, a laparotomy was selected as the surgical method. The immobility associated with FOP may predispose patients to postoperative urinary complications. In this case, catheter insertion was facilitated by repositioning the patient to ensure optimal exposure of the urethra. Furthermore, rigorous perineal care and early mobilization were implemented postoperatively. Consequently, no urinary tract infections were observed during the patient's hospital stay. This case report serves to enhance practitioners' awareness of FOP, a rare condition. It underscores the importance of proactively screening female FOP patients presenting with pelvic symptoms for gynecological diseases to prevent delays in surgical intervention. Upon hospital admission, it is crucial to optimize perioperative management actively. The anesthesia department should engage in thorough follow-up and collaboration, ensuring readiness for nasal intubation during surgery and having a tracheotomy plan readily available. Surgeons are advised to minimize operative time to the greatest extent possible. Given the constraints on patient positioning, laparotomy is preferred over laparoscopy in obstetric and gynecological surgeries, as precise and sharp dissection can significantly reduce bleeding risks. Multidisciplinary cooperation and collaborative nursing care are essential for the successful surgical outcome and discharge of the patient.

Fibrodysplasia ossificans progressiva (FOP) is a rare, benign disorder characterized by heterotopic ossification, typically occurring within muscle or soft tissue. The pathological hallmark of FOP is the formation of non-neoplastic, reactive bone and cartilage matrix, predominantly affecting young individuals [ 1 ]. Although the etiology of FOP remains incompletely understood, POF is generally categorized into traumatic and nontraumatic types. Patients experiencing traumatic and inflammatory triggers often exhibit ossification in large muscle groups, such as the thigh and upper arm [ 2 ]. Less commonly, nontraumatic cases have been documented without a clear history of trauma at diagnosis [ 3 , 4 ]. Primary clinical manifestations include localized muscle pain, swelling, and restricted movement. Diagnosis relies primarily on imaging modalities such as computed tomography (CT), but requires correlation with medical history and clinical examination to differentiate it from malignant bone or soft tissue tumors [ 5 ]. The existing medical guidelines emphasize the importance of early diagnosis and avoiding trauma, although symptomatic treatment aims to alleviate pain and optimize residual function. Palovarotene, as the first approved and guideline-recommended drug for ectopic bone formation (FOP), shows potential in reducing new ectopic bone formation. However, its long-term safety and efficacy still require further investigation [ 6 , 7 ]. In contrast, ovarian endometriosis is a prevalent gynecological condition, particularly among women of reproductive age. In China, it affects approximately 10% to 15% of this population [ 8 ]. Globally, prevalence ranges from 2% to 10% and is significantly higher in infertile women (approximately 50%) [ 9 ]. Ovarian endometriosis is hypothesized to result from the ectopic proliferation of endometrial tissue outside the uterine cavity. This ectopic tissue can form cysts on the ovaries, leading to symptoms such as pain and infertility [ 10 ]. The management of ovarian endometriosis cysts encompasses both pharmacological and surgical interventions. Pharmacological treatment primarily involves the use of oral contraceptives and progesterone to inhibit ovulation and reduce estrogen levels, thereby controlling symptoms [ 11 ]. Surgical intervention, particularly laparoscopic cystectomy, is frequently employed as a definitive treatment for ovarian endometriosis cysts [ 12 ]. Endometriosis and FOP are distinct pathological entities. Endometriosis is characterized by the formation of ectopic cysts in the ovaries, typically exhibiting estrogen dependence [ 13 – 15 ]. In contrast, FOP is marked by heterotopic ossification within soft tissues and is unrelated to reproductive hormone regulation. It is exceedingly rare for a single patient to concurrently present with both conditions in a clinical setting. This report aims to: (1) document the clinical diagnosis and treatment process, enhancing global practitioner awareness of this rare comorbidity; (2) examine and disseminate the unique challenges and coping strategies associated with gynecological surgery in the presence of fibroids; and (3) provide a practical reference for clinicians confronted with similar rare and complex complications in clinical practice.