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.