thecoma thecoma thecomas or theca cell tumors are benign ovarian neoplasms composed only of theca cells. histogenetically they are classified as sex cord-stromal tumours. thecomahigh magnification micrograph of a thecoma. h&e stain.specialtyoncology they are typically estrogen-producing and they occur in older women (mean age 59; 84% after menopause). (they can, however, appear before menopause.) 60% of patients present with abnormal uterine bleeding, and 20% have endometrial carcinoma. pathologic features low magnification micrograph of a thecoma showing compression of the ovarian cortex (right of image). h&e stain. grossly, the tumour is solid and yellow. grossly and microscopically, it consists of the ovarian cortex. microscopically, the tumour cells have abundant lipid-filled cytoplasm.