Angiomyofibroblastoma of the vulva in a 29-year-old woman: a case report of a rare entity with successful vaginal delivery.

A 29-year-old Chinese female patient, gravida 1 para 1 living 1(G1P1L1), came to our clinic, with a chief complaint of vulvar mass which was painless and gradually increasing in size for 6 years. One month prior, she underwent exploratory surgery for the vulvar mass at a local hospital, with a suspected diagnosis of a Bartholin’s cyst. But the initial diagnosis was ruled out due to intraoperative findings. The patient has no history of pelvic diseases or gastrointestinal diseases; additionally, she has no history of infectious diseases or trauma. She reported regular menstrual cycles, with a cycle length of 30–35 days and a menstrual duration of 5–7 days. There was no family history of similar diseases. Furthermore, the patient denied any history of blood transfusion, allergies, or other special medical conditions. Six years prior to the current presentation, at the age of 23 years, the patient first noticed a mass on her right labia majora, measuring approximately 2 cm in diameter. At this time, the mass occasionally decreased in size when she was in the supine position or at rest. On occasion, the mass exhibits cyclical changes corresponding to menstrual cycles, specifically increasing in size during menstruation. It did not exhibit erythema, swelling, or pain. Over the subsequent years, the mass gradually increased in size. However, the patient remained asymptomatic and did not seek medical evaluation during this period. Three years ago, she became pregnant. During pregnancy, the mass became slightly larger, about 8 cm at its largest, particularly when she experienced constipation. It was misdiagnosed as a Bartholin’s cyst. At 40 weeks of gestation, she presented with a small amount of bloody vaginal discharge, subsequently progressing to spontaneous rupture of membranes and the onset of spontaneous labor. During active labor, continuous electronic fetal heart rate monitoring was performed, with no abnormal patterns (e.g., late decelerations, variable decelerations) noted. A left lateral perineal episiotomy was performed to avoid trauma to the pre-existing vulvar mass (thereby preventing potential hemorrhage or mass rupture), which facilitated uneventful delivery of a live neonate. The neonate had a birth length of 51 cm, weight of 3450 g and Apgar scores of 10 at 1 min, 10 at 5 min, and 10 at 10 min. The overall labor course was uneventful: the first stage of labor lasted approximately 7 h, and the second stage lasted 20 min. No maternal complications were observed during the postpartum period, including postpartum hemorrhage and puerperal infection. Additionally, serial assessments of the vulvar mass during the puerperal period revealed no significant changes in its size, consistency, or appearance (e.g., no tenderness, ulceration, or exudation). Staring from six months after delivery, the vulvar mass decreased gradually, with its maximum diameter stabilizing at 6 cm. But during this period, the patient occasionally experienced vulvar itching, malodorous vaginal discharge, which prompted her to present to a local hospital one month prior for surgical resection of the vulvar mass. At this hospital, the mass was again diagnosed as a Bartholin’s cyst. Consequently, no additional preoperative imaging studies were conducted to further confirm this diagnosis. Intraoperatively, a 1.5-cm incision was made on the medial surface of the right labia majora to access the mass. But further intraoperative exploration revealed that the mass seemed to extend toward the pelvic deep region—beyond the expected anatomical scope of a typical Bartholin’s gland cyst. Subsequently, the mass were aspirated using a syringe, and the aspirated material was identified as a jelly-like substance. Given that the mass’s extent and borders could not be clearly defined at the time, and malignancy could not be ruled out, attempting to resect the mass carried the risk of damaging adjacent organs or causing tumor dissemination, the surgical team discussed the situation with the patient’s family intraoperatively. Following this discussion, the surigical procedure was suspended to facilitate further diagnostic evaluation (e.g., imaging, pathological consultation) to clarify of the mass’s tissue origin and extent. Unfortunately, the aspirated jelly-like material was not sent for cytological examination; consequently, no definitive pathological diagnosis was obtained from this aspirate either. Following discharge from the local hospital, the patient was transferred to our tertiary teaching hospital. On admission, her weight and height were 50 kg and 158 cm, respectively, yielding a body mass index (BMI) of 20.03 kg/m². Vital signs of the patient were stable and abdominal examination yielded unremarkable findings. Physical examination of the vulva identified a solid mass was in the mid-lower region of the right labia majora, measuring approximately 4.0 cm×6.0 cm×4.0 cm. The mass exhibited clear borders, moderate texture, good mobility, and no tenderness or erythema. A well-healed surgical incision scar was visible on the medial side of the right labium majora (from the prior operation). Digital rectal examination revealed that the mass did not invade the anus or rectum but appeared to extend toward the obturator region. Rectovaginal examination was unremarkable, and no inguinal lymphadenopathy was detected. Preoperative evaluations were performed for the patient, including complete blood count (CBC), coagulation function tests, as well as ultrasound and magnetic resonance imaging (MRI) of pelvic. Given the unclear tissue origin of the patient’s vulvar mass, we conducted tumor marker testing—not only to differentiate the mass from endometriosis and other tumors of uncertain nature but also to rule out potential associations with ovarian-derived tumors. Laboratory results indicated normal CBC and adequate coagulation function, tumor markers including carcinoma antigen (CA) 199, CA125, carcinoma embryonic antigen (CEA), alpha fetal protein (AFP), and human chorionic gonadotropin (HCG), were unremarkable. A superficial color Doppler ultrasound revealed a 3.5 cm×6.2 cm×3.9 cm hypoechoic mass in the subcutaneous layer of the right vulva, with clear margins, regular shape, and a blood flow resistive index (RI) of 0.58. The initial medical impression was a hemangioma, though the diagnosis remained uncertain—prompting the patient to undergo further contrast-enhanced ultrasound. It indicated that the right vulvar mass was likely a neoplastic lesion rather than a hemangioma. MRI of the pelvis demonstrated an irregular, heterogeneous-intensity mass involving the right vulva, with dimensions of approximately 3.3 cm×5.2 cm×4.5 cm and well-defined borders (Fig.  1 a and c). On dynamic contrast-enhanced MRI sequences, the lesion showed heterogeneous contrast enhancement. Importantly, no evidence of invasion into the obturator region, urethral orifice, vaginal mucosa, anus, or rectum was observed. Following the completion of all preoperative evaluations, a multidisciplinary team (MDT) consultation was conducted. Given the need to further clarify the nature of the mass promptly and the patient’s strong willingness to undergo surgical intervention, a second operation was performed one month after the initial surgery—by which time the incision from the initial procedure had fully healed. Fig. 1 T2 weighted images on magnetic resonance imaging (MRI) of the vulva before and after the sugery. a, b and c a well-circumscribed mass is identified beneath the skin of the right labia majora, presenting as heterogeneous intensity and approximately 3.3 cm×5.2 cm×4.5 cm before the surgery. a coronal view, ( b ) sagittal view, ( c ) transverse view.The arrows indicate the location of the lesion. d, e and f MRI shows that the vulvar structure is disordered, the right vulva presents as heterogeneous intensity after the surgery. d coronal view, ( e ) sagittal view, ( f ) transverse view T2 weighted images on magnetic resonance imaging (MRI) of the vulva before and after the sugery. a, b and c a well-circumscribed mass is identified beneath the skin of the right labia majora, presenting as heterogeneous intensity and approximately 3.3 cm×5.2 cm×4.5 cm before the surgery. a coronal view, ( b ) sagittal view, ( c ) transverse view.The arrows indicate the location of the lesion. d, e and f MRI shows that the vulvar structure is disordered, the right vulva presents as heterogeneous intensity after the surgery. d coronal view, ( e ) sagittal view, ( f ) transverse view The second surgery was performed with the patient in the lithotomy position under general anesthesia. Following routine disinfection and draping, a fusiform incision was made along the medial side of the right labia majora—at a distance from the mass margin to avoid intraoperative mass rupture—for the purposes of fully exposing the surgical field and completely removing the mass. The incision was then extended superiorly and inferiorly respectively along the long axis of the mass, with a total length of approximately 4 cm. Subsequently, the skin and subcutaneous tissue were incised layer by layer to expose the right vulvar mass. No significant mass enlargement, local invasion, or metastasis to adjacent tissues was observed. The mass was completely resected (Fig.  2 ) and sent for pathological examination. After confirming no active bleeding, the incision was closed layer by layer, and the operation was completed. Gross examination of the resected specimen revealed a solid, elastic-soft tumor, 4.0 cm×6.5 cm×3.5 cm in size, in the subcutaneous area. The tumor was well-circumscribed but non-encapsulated, with a homogenous, yellowish-gray cut-surface (Fig.  3 a and b). No hemorrhage nor necrosis was observed in the specimen. Postoperative pathological examination confirmed that the tumor was AMFB (Fig.  3 c and d). Immunohistochemical staining showed vimentin (+), desmin (+), smooth muscle actin ( SMA, foci +), estrogen receptor ( ER, +), progesterone receptor ( PR, +), B-cell lymphoma-2 ( Bcl-2, +), cluster of differentiation 34 ( CD34, vessel +), and S-100 protein (-). The Ki-67 proliferation index was less than 5%. Fig. 2 a A 4.0 cm×6.0 cm×4.0 cm vulvar swelling in the right major labia before the operation. b The vulva after the mass was resected by surgery a A 4.0 cm×6.0 cm×4.0 cm vulvar swelling in the right major labia before the operation. b The vulva after the mass was resected by surgery Fig. 3 a Macroscopic picture of the specimen measured by 4.0 cm×6.5 cm×3.5 cm in size. b On cut section, the tumor is well circumscribed and homogeneous, with a yellow to gray myxoid appearance. c and d Microscopy showing numerous thin-walled capillaries surrounded by spindle-shaped cells (Hematoxylin-eosin stain, ×100 and ×200, respectively) a Macroscopic picture of the specimen measured by 4.0 cm×6.5 cm×3.5 cm in size. b On cut section, the tumor is well circumscribed and homogeneous, with a yellow to gray myxoid appearance. c and d Microscopy showing numerous thin-walled capillaries surrounded by spindle-shaped cells (Hematoxylin-eosin stain, ×100 and ×200, respectively) The patient’s disease course and diagnostic nodes are summarized in the flowchart (Fig.  4 ). The surgical wound healed satisfactorily healing following the operation, with no complications such as incisional hematoma or infection. Three months after the second surgery, MRI of pelvic was performed to evaluate for potential recurrence. Imaging demonstrated vulvar structural disorganization and heterogeneous signal intensity in the right vulva(Fig.  1 d, e and f), but no radiological signs suggestive of AMFB recurrence were identified. The patient is currently being followed for 1 year with no evidence of recurrence. Fig. 4 Flowchart for disease course & diagnostic nodes of the vulvar AMFB patient Flowchart for disease course & diagnostic nodes of the vulvar AMFB patient

AMFB is a relatively rare benign mesenchymal tumor and curable with a simple excision. In this case, the AMFB had minimal impact on both pregnancy and vaginal delivery.

AMFB was first described in 1992 by Fletcher et al. [ 4 ]. It typically occurred in middle-aged women and frequently appeared as a benign, painless enlargement of the vulva. The lesion is characterized by a superficial anatomical location, slow-growth, and a low propensity for local recurrence. Notably, AMFB is clinically characterized by a lack of a distinct capsule—a feature that may increase the risk of residual tumor tissue after enucleation, even with careful surgical technique. Despite this, the disease itself has a low propensity for local recurrence: previous literature has reported that none of the patients with follow-up periods ranging from 1 to 25 years after simple resection developed recurrence [ 9 , 13 – 15 ]. Malignant degeneration of AMFB is also extremely rare, with only one case documented to date [ 16 ]. Given the tumor’s capsule-deficient nature (which raises potential residual risks) and its inherent tendency for late recurrence, long follow-up is crucial for detecting any evidence of recurrence. For this patient, during the first operation, only puncture aspiration of the mass was performed during the first operation—with only a small amount of its contents aspirated, and no resection of the mass itself was conducted. During the second operation (performed one month later, after the initial incision had healed), no significant mass enlargement, local invasion, or metastasis to adjacent tissues was observed. Three months after the second surgery, MRI of pelvic demonstrated no radiological signs suggestive of AMFB recurrence. Based on this clinical follow-up finding, we infer that the initial puncture aspiration did not induce recurrence or aggressive progression of the vulvar AMFB. We subsequently scheduled regular follow-up for the patient, and over one year of follow-up has elapsed with no evidence of recurrence. Nevertheless, an extended follow-up period is recommended for the patient to continuously monitor for any signs of recurrence, given AMFB’s inherent tendency for potential late recurrence. The AMFB requires differentiation from multiple other vulvar and pelvic diseases due to its nonspecific clinical and imaging features. Owing to its well-defined borders and lack of a peduncle, AMFB is frequently misdiagnosed as a Bartholin’s cyst —consistent with the present case, where the mass was initially suspected to be a Bartholin’s cyst. However, during the initial surgical exploration, the mass was identified as solid with a jelly-like stromal component—rather than cystic (i.e., fluid-filled) or mixed (solid and cystic)—prompting a reconsideration of the initial diagnosis. Subsequent ultrasound imaging revealed abundant blood flow signals, leading to a tentative clinical impression of a hemangioma. Previous literature has reported that vulvar myxoid or solid lesions similar to AMFB were often misdiagnosed as Bartholin’s gland cysts, hydroceles of the canal of Nuck, aggressive angiomyxomas, labial cyst, inguinal hernia, and mesenchymal tumors (e.g., lipomas and liposarcomas) [ 9 , 17 – 19 ]. In the present case, giving the variation of its size in relation to body position, constipation, and other factors, endometriosis and inguinal hernia cannot be completely ruled out preoperatively, but imaging finding did not support either diagnosis. Notably, a definitive diagnosis of AMFB relies on histopathological examination, which typically shows a proliferation of bland-looking spindle cells accompanied by abundant vascular structures [ 9 , 20 ]. No significant nuclear atypia is observed, and a low mitotic count with no necrosis is noted. Additionally, immunohistochemical staining consistently demonstrates that ER and PR were typically positive, which further supports the diagnosis of AMFB. Interestingly, the patient became pregnancy during the course of the disease and underwent a successful vaginal delivery. AMFB is characterized by benign biological behavior and slow-growth [ 21 ]. Accordingly, the lesions did not grow dramatically or undergo other degeneration during pregnancy. To date, there are no cases in the literature about the successful vaginal delivery of AMFB of the vulva, although some cases of AMFB in young women have been documented [ 11 , 12 ]. As is known, benign vulvar masses are not contraindications for vaginal delivery unless they obstruct the birth canal. Additionally, severe varicose veins in the vulva may elevate the risk of intrapartum hemorrhage. In the present case, the mass was located in the right vulva and did not interfere with the left perineal episiotomy performed during delivery. The lesion measured 8 cm in maximum diameter, presented as a soft, mobile mass, and exerted negligible compressive or obstructive impact on the birth canal. The delivery process was neither precipitous nor prolonged. Throughout the trial of labor, the patient maintained adequate physical stamina and demonstrated good cooperation with the midwives, which facilitated adequate and effective stretching of the perineal tissues, preserved their elasticity and supported optimal midwifery assistance. The newborn had a birth weight of 3,450 g (not classified as macrosomic), and no perineal lacerations, hematomas, or vulvar mass rupture/hemorrhage occurred during delivery. Giving the aforementioned factors, this case illustrates a successful vaginal delivery in a patient with vulvar AMFB. However, for pregnant women with AMFB who do not meet the above favorable conditions(e.g., large lesions causing birth canal obstruction, fixed lesions precluding episiotomy avoidance), vaginal delivery may pose an increased risk of birth canal lacerations and vulvar mass rupture. Therefore, cesarean section may be considered as an alternative delivery mode, depending on the lesion’s size, location, growth pattern, and degree of birth canal obstruction. Our study has several inherent limitations that should be acknowledged. First, as a single-case report, it lacks statistical power to draw generalizable conclusions regarding the management or prognosis of vulvar AMFB. Specifically, the patient’s successful vaginal delivery cannot be generalized beyond this case or similar patients. Furthermore, our relatively short follow-up may underestimate AMFB’s recurrence risk, as the tumor is known to potentially recur late (years after initial treatment), which our follow-up period does not fully capture.

Angiomyofibroblastoma (AMFB) is a relatively rare benign mesenchymal tumor predominantly observed in premenopausal women, with the majority of cases occurring in the vulva [ 1 , 2 ]. Additional cases have also been reported in other pelvic and extrapelvic sites, including the uterus, vagina, fallopian tubes, and even the inguinal region in male patients [ 3 ]. The lesions are well circumscribed and typically measure 0.5 to 12 cm in diameter [ 2 , 4 ], though larger lesions have been documented in select studies [ 5 , 6 ]. Clinically, AMFB lesions are typically benign, grow slowly and are often asymptomatic, causing no pain, vaginal bleeding, or abnormal discharge. However, when lesions reach a considerable size, symptoms may emerge—including localized vulvar pain, malodorous vaginal discharge, vulvar swelling, menorrhagia, and dyspareunia [ 7 , 8 ]. Histologically, AMFB is characterized by stromal cells without significant atypia and an abundant network of small blood vessels. Current hypotheses propose that AMFB originates from perivascular stem cells capable of differentiating into myofibroblasts and adipocytes [ 9 ]. Vulvar AMFB typically presents as a small lesion in middle-aged women, with a reported age at onset ranging of 32 to 60 years [ 9 , 10 ]. To date, only a few cases of AMFB in young women have been documented [ 11 , 12 ], and its impact on pregnancy and delivery remains poorly elucidated. Herein, we present a case of a 29-year-old woman diagnosed with vulvar AMFB who underwent pregnancy and vaginal delivery during the course of the disease.