thecoma cell granulosa-theca cell tumor cell An ovarian tumor predominantly composed of either granulosa cells (follicular cells) or theca cells, and often associated with excessive production of estrogen, with hyperplasia and carcinoma of the endometrium. When luteinized, i.e., having cells resembling those of the corpus luteum, it is known as luteoma. BTO:0002848 BrendaTissueOBO