Rare T-Cell Lymphomas

T-Cell lymphomas are a group of rare or, at least uncommon, hematologic malignancies comprising about 10–15% of all non-Hodgkin’s lymphomas in North America (6). Overrepresentation of certain subtypes such as natural killer (NK)/T-cell lymphoma makes them relatively more common in Asia (105, 106). As classification systems for lymphoid malignancies become more sophisticated, combining morphology, immunophenotype, molecular, and clinical information, more distinct subtypes of T-cell lymphoma have emerged. In the latest version of the WHO and World Health Organization-European Organisation for Research and Treatment of Cancer (WHO-EORTC) consensus on cutaneous lymphomas, there are at least 13 different subtypes of T-cell lymphoma (83).

In this chapter, we will focus on three of the rarest T-cell lymphomas: enteropathyassociated T-cell lymphoma, hepatosplenic T-cell lymphoma, and subcutaneous panniculitis- like T-cell lymphoma. Each of these lymphomas comprises less than 5% of all the T-cell lymphomas and fewer than 1% of all non-Hodgkin’s lymphomas, making them truly rare hematologic malignancies. Each section reviews increasingly well-described clinical and pathologic characteristics of these lymphomas. We also review strategies for management that are collected from case reports, small series, personal experiences, and retrospective reviews. Underlying the treatment discussions must be an awareness on the part of the reader of the inherent biases in case reports and small series and the lack of data available to formulate a preferred management approach.