An Infrequent Adenosarcoma Mimicking other Uterine Rhabdoid Tumours

Abstract

Uterine sarcomas are relatively rare and account for only 1-3% of all malignancies in the Female Genital Tract (FGT). Adenosarcomas of the uterus are uncommon accounting for only 5% of uterine sarcomas. They are considered less recurrent and less metastatic. However, those with sarcomatous overgrowth and heterologous differentiation are very rare, considered aggressive and need to be differentiated histologically from other sarcomas that mimic the same clinically and histologically. In the index case, a 50-year-old female presented with symptoms of pain in the abdomen and bleeding per vagina. Magnetic Resonance Imaging (MRI) showed a large polypoid solid mass in the endometrium, suggestive of a sarcoma. Positron Emission Tomography (PET) scan showed an Fluorodeoxyglucose (FDG) avid lesion in the endometrial cavity (SUV max-13.33). Total abdominal hysterectomy and salpingooophorectomy was performed. Histology showed a biphasic tumour (benign glands and malignant mesenchymal component) with rhabdomyoblastic differentiation and sarcomatous overgrowth. Presence of rhabdoid cells raises the possibility of other sarcomas with these features making the diagnosis challenging. Immunohistochemistry (IHC) confirmed it to be a high grade adenosarcoma with sarcomatous overgrowth. Desmin positivity was noted in the rhabdoid cells. Majority cases of adenosarcoma are low grade, the index case was however high grade with presence of heterologous elements and sarcomatous overgrowth. Neither radiology nor clinical features can reliably differentiate adenosarcomas from other uterine sarcomas. A definitive diagnosis can be made by understanding the overlapping morphological features and correlate it with IHC to reliably differentiate it with other similar looking uterine sarcomas.