Sarcomatoid (Spindle Cell) Carcinoma Arising in Mature Cystic Teratoma as a Mural Nodule: A Case Report

Mature cystic teratomas are the most common ovarian germ cell tumours.Malignant transformation is rare in mature cystic teratoma. Spindle cell/sarcomatoid carcinoma is an uncommon type of squamous cell carcinoma. A 45-year- old female presented with abdominal distention and discomfort. Magnetic Resonance Imaging (MRI) showed multiloculated cystic mass measuring 21x20x14 cm with heterogeneously enhancing solid component measuring 5x3.5 cm in right adnexal region. Excision of the mass done. Macroscopic examination showed irregular cystic mass containing pultaceous material and hair, and a mural nodule measuring 5x5 cm. On histopathological examination, the cyst wall showed mature teratomatous elements. Sections from mural nodule showed sheets of atypical spindle cells with increased mitosis and foci of necrosis. On immunohistochemical examination, the spindle cells showed patchy weak to moderate positivity for cytokeratin, 34 beta E12, CK5/6 and P40. Diagnosis of spindle cell/sarcomatoid carcinoma arising in mature cystic teratoma was given. Malignant transformation in mature cystic teratoma is rare and should be suspected in large sized tumours in older patients. Sarcomatoid carcinoma is an extremely rare form of secondary malignant neoplasm arising from mature cystic teratoma.