Disseminated peritoneal leiomyomatosis mimicking carcinomatosis: A case report

A 39-year-old female presented to her obstetrics and gynecology clinic for her annual routine exam and desire for permanent sterilization. The patient had no significant past medical or surgical history. Three prior pregnancies with vaginal delivery were uneventful with full term healthy babies. She was up to date with her screening Pap cytology and HPV testing was negative. There was no significant family history. Preoperative blood work up revealed nothing significant. No imaging studies were indicated. Patient consented to laparoscopic bilateral tubal ligation with Falope rings surgery and was scheduled for the procedure 15 days after the initial visit. During the operative procedure, incidental countless, small, single and coalescing firm, white-tan nodules were seen by laparoscopic imaging ( Fig. 1 a) in the abdominal peritoneal surface, more prominent in the right pelvic side wall but also ( Fig. 1 b) along the broad ligament and pelvic side wall of the left side. The lesions ranged in size from less than 1 mm to 10 mm. Due to the unexpected nature of the findings and high suspicion for carcinomatosis, the decision was made to randomly remove a few of the lesions for histopathology examination. The specimen submitted to the pathology laboratory consisted of two light tan tissue fragments. The first fragment ( Fig. 2 a) is a well-circumscribed, firm, tan nodule measuring 0.4 cm in greatest dimension with scant attached adipose tissue. The second fragment ( Fig. 2 b) consists of scant soft tissue with three firm, tan nodules measuring from less than 1 mm to 0.4 cm in greatest dimension. Light microscopy examination ( Fig. 3 a) reveals a rounded tumor with well-defined border without capsule surrounded by mature adipose tissue. A histopathology higher power view ( Fig. 3 b) shows a fasciculated spindle cell lesion with plump cells with tapered ends and rare perinuclear vacuolization. There is no evidence of necrosis, mitosis or any significant atypia. All the nodules looked morphologically identical. Immunohistochemical stains show the lesion cells were positive for desmin ( Fig. 4 a), negative for S100 ( Fig. 4 b) and pankeratin (not shown), and with a low KI-67 proliferation index (not shown). The staining profile confirmed the muscle origin of the cells, leading to a final diagnosis of leiomyoma. Given the disseminated nature of the lesions, the criteria for Disseminated Peritoneal Leiomyomatosis are met. Fig. 1 Laparoscopic intraoperative gross appearance of peritoneal nodules in vivo involving the right pelvic side wall (a) and left broad ligament (b). Fig. 1 Fig. 2 Low power view (x10) of the removed peritoneal nodules measuring 4 mm (a) and ranging in size from less than 1 mm to 4 mm (b). Fig. 2 Fig. 3 (a) Histological examination of nodule (x100) shows a well circumscribed unencapsulated neoplasia with adjacent adipose tissue. (b) Histologic examination of nodule (x400) shows a tumor composed of interlacing fascicles of plump spindle cells with rare perinuclear vacuolization without atypia, necrosis or mitosis. Fig. 3 Fig. 4 Histological examination of immunohistochemistry stained peritoneal nodule (x20) shows (a) positive (brown color) staining for desmin and (b) negative (blue color) staining for S-100. Fig. 4 Laparoscopic intraoperative gross appearance of peritoneal nodules in vivo involving the right pelvic side wall (a) and left broad ligament (b). Low power view (x10) of the removed peritoneal nodules measuring 4 mm (a) and ranging in size from less than 1 mm to 4 mm (b). (a) Histological examination of nodule (x100) shows a well circumscribed unencapsulated neoplasia with adjacent adipose tissue. (b) Histologic examination of nodule (x400) shows a tumor composed of interlacing fascicles of plump spindle cells with rare perinuclear vacuolization without atypia, necrosis or mitosis. Histological examination of immunohistochemistry stained peritoneal nodule (x20) shows (a) positive (brown color) staining for desmin and (b) negative (blue color) staining for S-100. The rarity of the disease and uncertainty of the appropriate post-operative follow up prompted a referral to more advanced specialized care by an oncologic Ob/Gyn surgeon familiar with the condition. Postoperative workup included unrevealing PET and abdominal CT studies. Since she remained asymptomatic and all her lesions are small and not impinging in other organs, there was no indication for debulking surgery. The patient was prescribed gonadotropin-releasing hormone agonist treatment in an attempt to stunt the growth of the tumor nodules. She was placed in interval surveillance imaging follow up aiming to identified any rapidly growing lesion that will trigger more aggressive therapy.

Matthew Lee (writing paper, final approval) Gabriella Morey (writing paper, final approval) Hector Lopez (writing paper, final approval) Robert Bass (data collection, final approval) Susana Ferra (study design/concept, data analysis, writing paper, final approval). Matthew Lee (writing paper, final approval) Gabriella Morey (writing paper, final approval) Hector Lopez (writing paper, final approval) Robert Bass (data collection, final approval) Susana Ferra (study design/concept, data analysis, writing paper, final approval).

Ethics approval of case reports or case series manuscripts is not required by the HCA Healthcare GME Institutional Review Board.

Nothing to declare.

Susana Ferra.

Disseminated Peritoneal Leiomyomatosis frequently presents in women of reproductive age with a history of laparoscopic myomectomy, hysterectomy for leiomyoma, menstrual irregularities or hormonal stimulation. Though our patient had no prior medical or surgical history and was asymptomatic, incidental lesions mimicking carcinomatosis macroscopically were found resulting in benign leiomyomas microscopically. Despite the rarity of the disease, DPL should be included in the differential diagnosis of disseminated peritoneal nodules along with the usual culprits leiomyosarcoma, endometriosis, and peritoneal carcinomatosis since they all share a similar macroscopic appearance. Treatment includes medical hormonal suppression of the tumors and surgical options based on patient's clinical presentation. Follow-up is necessary due to possible malignant transformation and recurrences. Histopathology examination with or without immunohistochemical techniques remains the gold standard for the diagnosis and subsequent management decisions of the patients. Increased awareness by all medical professionals could potentially prevent unnecessary interventions and anxiety for the patients and treating clinicians.

This research was supported (in whole or in part) by HCA Healthcare and/or HCA Healthcare-affiliated entities. The views presented in this article represent those of the authors of the article and do not necessarily represent the official views of HCA Healthcare or any of its affiliated entities. Written informed consent was obtained from the patient for publication of this case report and accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal on request. This surgical case report was completed with guidance from the 2023 SCARE guidelines [ 17 ].

Disseminated Peritoneal Leiomyomatosis (DPL) also known as Leiomyomatosis Peritonealis Disseminata (LPD) was first described by Wilson and Peart in 1952 [ 5 ] as a benign condition, characterized by small nodules of smooth muscle cells on the abdominal organs and the peritoneum. It was later named by Taubert in 1965 [ 6 ]. There have been approximately 150 cases reported in the literature, most of them single case reports. One of the largest series to date is a cohort of 13 cases from Peking Union Medical College Hospital in Beijing China. The study focuses on iatrogenic DPL, a recently recognized entity related to prior laparoscopic myomectomy with uncontrolled morcellation [ 7 ]. Due to DPL's relatively low prevalence and macroscopic appearance in conjunction with the location of the smooth muscle cell deposits, it can easily lead to a misdiagnosis of malignancy [ 1 , 8 , 9 ]. There are multiple proposed etiologies of DPL such as via the metaplasia of multipotent mesenchymal stem cells within the peritoneum, genetics, iatrogenic implantation after a laparoscopic leiomyoma morcellation procedure, or through hormonal stimulation [ 10 , 11 ]. Although DPL has been documented in women of postmenopausal age and even men, it is most prevalent in women of reproductive age who are exposed to high levels of exogenous and endogenous gonadal steroids. It has been reported in women with a history of oral contraceptive use, during pregnancy or in the setting of fibrothecoma, which over time can stimulate the differentiation of smooth cells within the abdominal organs or peritoneum [ 1 , 12 , 13 ]. Our patient had no history of prior surgeries but did have a long history of oral contraceptive use, one of the known risk factors for the disease. Clinical imaging studies of these lesions are an integral factor in determining the extent of disease and subsequent intervention/treatment. On CT, multiple solid and complex soft tissue masses showing heterogeneous attenuation with variable enhancement can be seen. However, when degeneration, necrosis, or implantation occurs, the enhancement becomes heterogeneous and can mimic peritoneal carcinomatosis [ 1 , 14 ]. On MRI, DPL nodules emit hypointense signals like that of skeletal and smooth muscles. Positron emission tomography is the gold standard in differentiating DPL from malignant peritoneal disease, demonstrating the absence of Fludeoxyglucose (FDG) uptake in nodules in DPL and avid FDG uptake in malignancy [ 2 ]. The patient underwent an abdominal CT study revealing multiple sub centimeter homogenous nodules in the pelvis peritoneum without a dominant mass or features of degeneration. Her PET study was reported as negative with no areas of abnormal uptake. Her imaging findings correlated with the histopathologic diagnosis of a benign condition. Histological examination in prior cases of DPL nodules have shown proliferation made of interlinking bundles and whorls of benign spindle cells with profuse eosinophilic cytoplasm, nonatypical elongated nuclei with minimal mitoses, and focal areas of hyalinization separated by vascularized connective tissue and cells. Lesions have been found to express positivity for estrogen receptors, progesterone receptors, Bcl-2, vimentin, smooth muscle antigen, smooth muscle actin, desmin, and caldesmon, all consistent with leiomyoma [ 3 ]. Microscopic analysis of our patient's tissue revealed a fasciculated spindle cell lesion with a well-defined border without malignant features such as necrosis, mitosis or cellular atypia. Immunohistochemical stains show the tumor cells were positive for desmin confirming muscle origin. Benign muscle tumors, like in our case, are leiomyomas, also known more commonly as fibroids. Tumors of muscle origin with malignant features are leiomyosarcomas, the closest histologic mimicker to our case. In a case of DPL, once muscle origin is proven, the main concern should be for the conclusive exclusion of leiomyosarcoma. Any of the countless DPL nodules has the potential for malignant transformation to a leiomyosarcoma highlighting the need for long term close follow up. Approximately 2–5 % of the cases may have a neoplastic transformation [ 1 , 15 ]. Other entities in the differential diagnosis includes carcinomatosis and endometriosis, with significant macroscopic appearance resemblance. Carcinomatosis is a dissemination of an epithelial malignancy in the peritoneal cavity as an advance stage of the disease. It is not common as an incidental finding in an otherwise asymptomatic patient. Endometriosis is the presence of ectopic endometrial tissue outside of the uterine cavity that presents as few or numerous peritoneal deposits mimicking DPL and carcinomatosis. Despite overlapping gross appearance, these entities are easily differentiated from DPL upon histopathologic examination by the presence of epithelial elements and positive immunohistochemistry for keratins. Treatment should be personalized as some patients may not require therapy due to low risk of malignant transformation, with progression in only 3–5 % of cases [ 3 ]. However, close surveillance and reduction of hormonal stimulus via a conservative approach is recommended. Medical treatment with gonadotropin-releasing hormone agonist is first line. Ulipristal acetate, a selective progesterone receptor modulator, has also been used [ 4 ]. Surgical castration with or without removal of the tumor masses can be done if failed medical management [ 2 ]. When DPL is not managed properly, it can lead to complications such as bleeding, chronic constipation, and infertility [ 16 ]. Therefore, the management of DPL should be based on patient's preference.

Disseminated Peritoneal Leiomyomatosis (DPL) is a benign proliferation of numerous solid peritoneal lesions along the abdominopelvic cavity comprised of smooth muscle and connective tissue [ 1 , 2 ]. Since first being described in 1952, with less than 150 cases reported in the English literature, the exact etiology remains unknown. Hormonal stimulation, as seen in premenopausal women with increased levels of gonadal steroids, oral contraceptive use, pregnancy, or ovarian neoplasia have been implicated in prior cases [ 3 ]. Iatrogenic causes have also been explored in the setting of vascularization of fibroid fragments or surgical debris in the peritoneum or mesentery after morcellation [ 4 ]. Most patients with DPL are asymptomatic while others present with non-specific symptoms such as abnormal uterine bleeding and abdominal discomfort [ 2 ]. Preoperative diagnosis of DPL is virtually impossible since the condition is usually incidentally diagnosed during surgery. Therefore, intraoperatively, it can be easily confused with disseminated intra-abdominal malignancies. Although generally a benign condition, there is a known risk of progression, recurrence and the possibility of malignant transformation and metastasis. Meticulous investigation and accurate histopathology diagnosis are of utmost importance for the establishment of the correct diagnosis and exclusion of the much more common malignant peritoneal nodules due to carcinomatosis and leiomyosarcoma. We present a 39-year-old female who consulted a local obstetrics and gynecology surgeon for desired sterilization, found incidentally to have multiple nodules suspicious for carcinomatosis at the time of surgery. Histopathology evaluation of the lesions revealed findings consistent with tissue of leiomyomas, alluding to diagnosis of DPL.

Nothing to declare.