CD30 positive (non-anaplastic) peripheral T cell lymphoma of the thyroid gland

Primary non-Hodgkin's lymphoma of the thyroid gland are infrequent tumors. They almost exclusively derive from B cells of mucosa-associated lymphatic tissue and only a very small minority of them are T cell lymphomas. CD30 molecule, other than in Hodgkin's and Reed-Sternberg cells, is strictly associated with anaplastic large cell lymphoma and ALK lymphomas, the latter being identified by the monoclonal antibody ALK1. We report a case of CD30- positive non-anaplastic (ALK1-negative) peripheral T cell lymphoma of the thyroid gland and speculate on aspects concerning diagnosis and the morphologic and immunohistochemical findings.