Correspondence Malignant eccrine poroma To the Editor

I read with interest the article on malignant eccrine poroma, published in the May issue of Saudi Medical Journal.1 I am however, unconvinced, based on the photographic evidence submitted (Figure 1), that the original skin lesion was a benign eccrine poroma. My reasoning for this is best described in the following 3 points. The original foot lesion is described as being an eccrine poroma (benign), and Figure 1 demonstrates its histological appearances. This shows what appears to be the deep aspect of the lesion, which adopts a nodular growth pattern. The tumor cells show significant cytoplasmic vacuolation and some degree of nuclear pleomorphism. There are perhaps (not entirely clear at this magnification) one or 2 mitotic figures. One can see a tumor nodule pushing into the subcutaneous fat. Based on this constellation of histological appearances, one would have to question the appropriateness of a completely benign diagnosis in this case. Furthermore, if indeed, this is a benign eccrine poroma; an image showing the cords and broad columns of basaloid cells extending down from the epidermis would be more suitable. According to the authors, this was a case, which demonstrated malignant transformation of a benign eccrine poroma after incomplete excision. Malignant eccrine poroma usually arises de-novo, although approximately 16-17 % arise from a preexisting benign eccrine poroma. In cases of transformation, the development of a malignant phenotype appears to take many years, even decades. It is therefore, unusual for a benign eccrine poroma to transform to a malignant eccrine poroma within 5 months. Furthermore, in cases of transformation, one can usually identify some benign eccrine poroma elements adjacent o the malignant eccrine poroma. Did the authors discover this? For the reasons discussed above, I am doubtful that the original lesion was in fact, a purely benign eccrine poroma, and that it instead already harbored some malignant features. I would ask the authors to review all the relevant histology with this point in mind