Uterine malakoplakia diagnosed in a cervical Pap smear

very few cases have been reported in the skin. The cytological features of signet ring SCC have not been described to date. Signet ring cells are commonly found in adenocarcinoma, especially gastric adenocarcinoma. The intracytoplasmic vacuoles in this case were morphologically similar to those of adenocarcinoma, but the vacuoles were negative for mucin and the cytoplasmic characteristics were different from those of adenocarcinoma. However, the vacuoles of mesothelioma cells can be barely distinguishable from signet ring SCC owing to the similar cytoplasmic characteristics of SCC and malignant mesothelioma. We have described a rare case of pulmonary SCC consisting of acantholytic tumour cells and signet ring cells. The FNA cytology of acantholytic SCC with signet ring cell component showed scattered and loosely aggregated cells with windows, linear cell arrangements and cell engulfment. The tumour cells were round and had central nuclei, prominent nucleoli, an optically dense cytoplasm, endo–ectoplasmic demarcation, occasional intracytoplasmic vacuoles and rare parakeratosis/dyskeratosis. The cytological features of acantholytic SCC with signet ring cells can be similar to those of epithelioid malignant mesothelioma. Immunostaining including squamous and mesothelial cell markers may be required to confirm this tumour subtype.