Cutaneous inflammatory pseudotumor (plasmocytoid granuloma) [Pseudotumore infiammatorio cutaneo (granuloma plasmocitoide)]

Cutaneous inflammatory pseudotumor is a rare benign condition that should be macroscopically differentiated, from dermatofibroma and metastates of carcinoma and, histologically from cutaneous lymphomas and other more aggressive diseases. We report herein the case of a 63-year-old man with a painless nodule of the left arm skin with a rapid growth (1 month ago). The histological examination revealed a well-defined dermal nodule of plasmacytoid cells, without connection or infiltration of the epidermis. At high power the polymorphous cellular infiltrate was, constituted by medium- small elements with widespread features of lympho-plasmocytoid differentiation or clear plasmacellular features. Immunohistochemical analysis showed a polyclonal cytological pattern with expression of both immunoglobulin light chains κ, e λ by plasmacytoid and admixed B and T lymphocytes. The final diagnosis was Plasmocytoid granuloma an entity that is recognized within the so called "Cutaneous inflammatory pseudotumor" together with the myofibroblastic tumor.