Leiomyomatosis peritonealis disseminata: a rare disease with a difficult diagnosis.

Leiomyomatosis peritonealis disseminata (LPD) is a rare condition, characterised by the proliferation of peritoneal smooth muscle nodules. LPD is a benign disease with a low rate of malignant degeneration. We describe the case of a 46-year-old, asymptomatic, woman presenting with a mass on the left renal hilum, identified by ultrasound. A CT scan showed three nodules near the left kidney, a mass anterior to the vena cava and bilateral iliac nodules. Biopsy revealed a mesenchymal low-grade tumour. The patient underwent a left nephrectomy and excision of the other masses. The histological diagnosis revealed smooth muscle nodular proliferation with no malignant features, compatible with LPD. The differential diagnosis between LPD and metastatic leiomyosarcoma is sometimes very difficult because they are clinically very similar and even on histology the diagnosis can be tricky. Treatment is conservative in most cases, with surgical excision reserved for high-risk patients.

carcinogenesis, gynecological cancer, general surgery

Leiomyomatosis peritonealis disseminata (LPD) is a rare smooth muscle benign tumour, characterised by the proliferation of smooth muscle cell nodules throughout the peritoneal and omental surfaces.1–3 The pathophysiology of the disease is not fully characterised but a possible origin from submesothelial multipotent cells has been suggested. Association between LPD and endometriosis has been reported, which favours a common origin for both lesions.2 4 5 The diagnosis of LPD is difficult due to its clinical resemblance to peritoneal carcinomatosis or metastatic lesions.1 Although rare, LPD can degenerate into malignancy.1 6 Case presentation We present the case of a 46-year-old woman, with no previous medical or surgical history and not under oral contraceptives. The patient had a routine abdominal ultrasound prescribed by her family physician, which showed a 3 cm mass at the left renal hilum, she was forwarded to our institution, to further assess this mass. A CT scan showed: ‘… three adjacent nodular formations between the left kidney and the aorta in a patient with two patent renal veins. The scan also showed an heterogeneous tumorous formation with 51×41×19 mm, immediately anterior to the vena cava (figure 1) and two formations compatible with enlarged lymph nodes adjacent to the iliac vessels bilaterally’. The caval lesion was deemed too risky to biopsy, so a CT-guided biopsy was taken from one of the left renal hilum masses. Histopathology was compatible with a low-grade mesenchymal neoplasm with muscular differentiation. The case was discussed at the multidisciplinary team meeting and the patient was proposed to undergo exploratory laparotomy with possible left nephrectomy. Treatment During the exploratory laparotomy, no new lesions were identified and both the uterus and adnexa presented without macroscopic alterations. A left nephrectomy was performed along with the excision of the precava lesion (figure 2) and both iliac lesions. Since the lesions were in close proximity to the renal artery and vein and there was a presumed diagnosis of malignancy, we decided to perform a nephrectomy for oncological reasons. The patient had no postoperative complications and was discharged on postoperative day 6. Outcome and follow-up The histopathological analysis revealed cells with elongated nuclei, without nuclear atypia (figure 3). The determined ki-67 of <3%, was indicative of insignificant mitotic activity. The immunohistochemical profile showed CD34, actine and caldesmon positivity (figures 4–5). In conclusion: ‘smooth muscle nodular proliferation with no malignant features, compatible with the diagnosis of Leiomyomatosis peritonealis disseminata’. Estrogen receptors (ER) and progesterone receptors (PR) were negative in the specimen. The patient is currently on the first year of follow-up with no signs of recurrence.

LPD is a very rare condition that was first described in 1952 by Wilson and Peale7 with ~100 cases described in the literature.1 The actual incidence of the disorder can be underestimated due to its asymptomatic nature.6 LPD represents a benign proliferation of smooth muscle cells in the peritoneal surface.8 Although benign, it is postulated that LPD could degenerate into malignancy, and the association between LPD and leiomyosarcoma has been reported.6 9 The majority of cases happen in premenopausal women, but there have been reports of cases in postmenopausal women and even men.1 6 8 The aetiology and pathophysiology of LPD is not totally clear but it is thought to originate from metaplasia of submesothelial multipotent mesenchymal cells.1 2 6 Pregnancy and prolonged use of oral contraceptive increase the risk of LPD, which supports the association between the exposure to high levels of estrogens and the development of LPD. Oestrogen and progesterone receptors have been identified in LPD cells, which further supports this association.1 8 Laparoscopic hysterectomy with morcellation may increase the risk of tumour implantation and dissemination, with cases of LPD being reported several years after myomectomy or hysterectomy.1 Several reports have also shown an association between LPD and endometriosis.4 5 Patients are usually asymptomatic or have non-specific symptoms such as abdominal discomfort or distention.1 2 6 8 CT and MRI can be useful in the preoperative setting to differentiate between LDP and peritoneal carcinomatosis, although they are of limited utility for the differential diagnosis of malignancies.1 10 Preoperative biopsy is essential but, as in our case, the differential diagnosis between LPD and low-grade leiomyosarcoma can be very difficult, which can impact the management of the disease.1 Besides leiomyosarcoma, the differential diagnosis of LPD includes peritoneal carcinomatosis, lymphoma, benign metastasising leiomyomas or other peritoneal tumours.1 10 Most cases of LPD can be managed conservatively, as spontaneous regression has often been described. This is the preferred approach in asymptomatic patients.6 8 Due to its role in LPD, hormonal stimulus should be minimised (stopping oral contraceptives, chemical or surgical castration).1 6 8 Surgical treatment, with resection of tumours is strongly recommended in cases with high risk of malignant degeneration, such as no exposure to exogenous or increased endogenous estrogens, no history of uterine leiomyomas and no oestrogen or progesterone receptors in the LPD nodules.1 6 Systemic chemotherapy has been described as a viable treatment option in patients with unresectable disease, but the experience with this course of treatment is limited.11 Follow-up with CT/MRI is recommended for high-risk patients.1 Learning points. Leiomyomatosis peritonealis disseminata (LPD) is a very rare benign condition with a minor risk of malignant degeneration. LPD can mimic metastatic leiomyosarcoma and peritoneal carcinomatosis. Its differential diagnosis is difficult even in biopsy specimens. High-risk patients should have surgical excision of the nodules. Footnotes Contributors: DMJ: data acquisition, writting and review. JSP and EF: data acquisition and review. ICF: review. Funding: The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors. Competing interests: None declared. Provenance and peer review: Not commissioned; externally peer reviewed. Patient consent for publication: Obtained.

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