Fine-needle aspiration cytology of abdominal wall endometriosis: a study of 10 cases.

While about 15% of menstruating women develop endometriosis, abdominal wall endometriosis is relatively rare. We present 10 cases of abdominal wall endometriosis diagnosed by fine-needle aspiration (FNA) cytology and confirmed by subsequent surgical excision. A palpable abdominal wall mass was the most common symptom, followed by pain. Nine cases were associated with previous surgery. The smear showed glandular epithelial cells and spindle or ovoid stromal cells accompanied by macrophages in eight cases. The nucleus was round-to-oval and the nucleolus was inconspicuous. Mitosis was not observed in any case. In two cases, which were suspicious of malignancy on FNA, the epithelial cells showed anisonucleosis, hyperchromasia, and small conspicuous nucleoli. The stromal cells were spindle or ovoid in shape, without metaplastic changes. Histiocytes were noted in nine cases and hemosiderin-laden histiocytes were noted in two cases. The proportion of inflammatory cells varied. FNA diagnosis of abdominal wall endometriosis is possible when the cytological features are interpreted cautiously, together with the patient's clinical history. An accurate diagnosis on FNA will prevent unnecessary surgery.