Primary retroperitoneal lipoleiomyoma: a rare differential of retroperitoneal fat-containing lesions

Abstract Lipoleiomyomas are rare benign tumors most commonly seen in uterus, with extra-uterine locations like primary retroperitoneal lipoleiomyoma being a rare sight. Radiological imaging shows presence of large well-defined retroperitoneal fat and non-fat soft tissue containing mass. Histopathology confirms the diagnosis by showing smooth muscle cells and adipose tissue without atypia. We present a case of a 64-year-old diabetic female who presented with post-menopausal spotting and vague abdominal pain. Ultrasound and contrast enhanced MRI abdomen and pelvis revealed a large well-circumscribed retroperitoneal lesion with internal fat and non-fat soft tissue areas, without obvious signs of adjacent organ infiltration/lymphadenopathy/distant metastasis, with suspicious neoplastic lesion in the cervix. Imaging diagnosis of a well-differentiated liposarcoma with possible carcinoma cervix was made. Pre-operative cervical biopsy dispensed squamous cell carcinoma. Surgical excision of the retroperitoneal mass was done, with post-operative histopathology diagnosis suggesting lipoleiomyoma. Although a rare entity, lipoleiomyoma should in kept in differential of radiologically detected well encapsulated/ non-infiltrating retroperitoneal fat-containing lesions.