ALK-negative systemic intravascular anaplastic large cell lymphoma presenting in the skin.

Systemic cases of the CD30-positive T-cell neoplasm, anaplastic large cell lymphoma (ALCL), are typically anaplastic lymphoma kinase (ALK)-positive. The failure to express ALK protein has been shown to portend a worse prognosis. We describe a case of ALK-negative systemic ALCL that presented as a violaceous plaque on the scalp of a 79-year-old man. Interestingly, the neoplastic cells were confined largely within vascular spaces, a configuration that is exceedingly rare in the skin and is more typically seen with intravascular large B-cell lymphoma. In addition, bcl-2 immunohistochemical staining was strongly positive in this case, which may portend a more aggressive clinical course. To our knowledge, this report represents the first case of an ALK-negative ALCL to present intravascularly in the skin. Therefore, the recognition of systemic anaplastic T-cell lymphoma present within the intravascular spaces is important to avoid misdiagnosis.