Malignant mural nodule in ovarian mucinous neoplasms - Needle in a haystack

Abstract

Ovarian mucinous tumors with mural nodules are very rare surface epithelial-stromal tumors. The mural nodules are divergent neoplasms that may be benign or malignant. The latter may be in the form of a sarcoma, carcinosarcoma, anaplastic carcinoma, or a variety of other recognized histotypes of carcinoma. They represent the part of the tumor which is undergoing divergent differentiation or collision tumors. Here, we report two such cases to discuss the histo-morphological and immunohistochemical features with prognosis. Case 1 is a 15-year-old female presented with right sided abdominal mass for 4 months. She underwent right salphingo-oophorectomy. On histopathological examination -borderline mucinous neoplasm of ovary with a mural nodule showing rhabdoid differentiation. On immunohistochemistry – malignant mural nodule confirmed to be an anaplastic carcinoma, rhabdoid type. Case 2 is a 16-year-old female presented with abdominal mass associated with pain for the past 1 year. She underwent a left salphingo- oophorectomy with left groin node debulking and abdominal wall deposits excision. On histopathological examination – mucinous carcinoma of ovary with a malignant mural nodule showing morphological features of carcinosarcoma. On immunohistochemistry – malignant mural nodule confirmed to be a sarcoma-like mural nodule, pleomorphic and spindle cell type. A malignant mural nodule can be associated with poor prognosis regardless of the benignity of the associated mucinous tumor. Hence, careful and meticulous examination of this rare lesion within a mucinous cystic tumor supplemented by immunohistochemistry aids in the sometimes, difficult differential diagnosis among these types of mural nodules.