Endometriosis involving the rectus abdominis muscle and subcutaneous tissues: fine needle aspiration appearances

Endometriosis is defined as functioning endometrial tissue outside the uterine cavity. It occurs in up to 15% of menstruating females and in most cases is located within the pelvis. Endometrial implants, however have been described in soft tissues, particularly in the skin and subjacent tissues of surgical scars, and diagnosis might be problematic. A 32 aged female presented with a suprapubic abdominal mass, which appeared suddenly after exercise. Fine needle aspiration was performed. Epithelial sheets were shown in direct aspirates. No evident endometrial stromal cells were seen. CD10 immunostaining in additional cell block preparations using a commercial antibody gave positive results. The cell pattern and immunocytochemical profile suggested a cytodiagnosis of endometriosis. The patient was administered with leuprolide acetate. She experienced adverse effects related to estrogen deficiency. Medical treatment was discontinued and the patient underwent surgical excision. Histological sections revealed endometrial glands surrounded by stroma and embedded in fibrous connective tissue. With optimal preparations a confident cytological diagnosis of endometriosis may be established easily, allowing correct treatment of the disease and, in selected cases, planning of preoperative pharmacologic therapy.