The protean spectrum of non‐Hodgkin lymphomas with prominent involvement of subcutaneous fat

Background:  Subcutaneous T‐cell lymphoma (STCL) represents a controversial entity and a confused concept in the field of cutaneous T‐cell lymphomas (CTCLs). Recently, α/β + /CD8 + STCL has been recognized by the new World Health Organization (WHO)–European Organization for Research and Treatment of Cancer (EORTC) classification of primary cutaneous lymphomas as a distinct entity in the group of CTCLs. Observations:  We reviewed a series of 53 biopsies from 26 patients (F : M = 19:7; median age: 48; range 18–87) of cutaneous B‐ and T‐cell lymphomas characterized by prominent involvement of the subcutaneous tissue. We could classify our cases according to the following seven categories – (i) STCL: n = 16; (ii) extranodal NK/T‐cell lymphoma, nasal type: n = 2; (iii) cutaneous γ/δ T‐cell lymphoma: n = 2; (iv) anaplastic CD30 + large T‐cell lymphoma: n = 1; (v) diffuse large B‐cell lymphoma, secondary cutaneous: n = 3; (vi) lymphoplasmacytic lymphoma, secondary cutaneous: n = 1; (vii) specific cutaneous manifestations of myelogenous leukemia: n = 1. Conclusions:  We demonstrated the protean nature of lymphomas with prominent involvement of the subcutaneous fat tissues. The term STCL should be restricted to a homogeneous group of cases characterized morphologically by an exclusive involvement of subcutaneous tissues, immunohistochemically by a T‐cytotoxic α/β phenotype, and biologically by a relatively good prognosis.