Erythrophagocytic tumour cells in melanoma and squamous cell carcinoma of the skin

Aims: Erythrophagocytosis is a characteristic feature of tumour cells in malignant histiocytosis, some leukaemias, lymphomas, and also reactive histiocytes in the haemophagocytic syndrome associated with a variety of infections and neoplasms, It has also been found exceptionally In metastatic malignant epithelial cells in bone marrow and lymph nodes. We present two cases, a cutaneous malignant melanoma and an acantholytic squamous cell carcinoma, in which erythrophagocytosis by tumour cells was demonstrable by both light and electron microscopy. Methods and results: The melanocytic and squamous nature of these cells was supported by the immunohistochemical detection of HMB45, S100, and NKI-C3 in the former, and cytokeratin and EMA in the latter, and at ultrastructural level by the presence of melanosomes and tonofilaments, respectively. Conclusions: This is, to our knowledge, the first documented report of erythrophagocytic tumour cells in human melanomas and primary carcinomas. Biological considerations apart, this unusual feature can prove to be of value to avoid a misdiagnosis of a variety of haematopoietic malignancies.