Subcutaneous @entity784 (SCPTCL) is characterized by primary involvement of the subcutaneous fat in a manner mimicking @entity3139 . We studied 16 cases of this @entity706 to define its immunophenotypical profile as well as cellular origin. Involvement of the subcutaneous fat in a lacelike pattern with neoplastic cells rimming individual fat spaces was present in all cases. All 16 cases were of T cell phenotype. Thirteen of the 16 cases were @entity405 +, whereas three were negative for both @entity404 and @entity405 . Twelve cases were stained for betaF1; of these, eight were betaF1+ and four were betaF1-. Focal staining for @entity2940 and @entity5823 was seen in 2 of 13 and two of eight cases, respectively. Intense diffuse positivity for the cytotoxic granular proteins @entity13433 ( @entity13433 ) and perforin was present in all cases, indicating an origin from cytotoxic T lymphocytes. Ten cases studied for Epstein-Barr viral sequences were negative. Eight of 9 cases with amplifiable DNA showed a clonal TCR gamma gene rearrangement by polymerase chain reaction. Controls included seven cases of benign @entity3139 and seven other peripheral T cell lymphomas involving the skin and subcutaneous tissues: two peripheral T cell lymphomas, not otherwise specified (PTL,NOS), four @entity2108 ( @entity2108 ), one T/NK cell @entity706 . The seven cases of @entity3139 lacked cytological atypia and were characterized by an admixture of @entity404 + and @entity405 + cells with interspersed aggregates of L26+ B cells. Only infrequent cells showed staining for @entity13433 and perforin. In the control cases of @entity784 , the infiltrate had a tendency for dermal and sometimes even epidermal involvement, with sheeting out of malignant cells, in contrast to the characteristic subcutaneous localization and rimming of fat spaces noted in SCPTCL. The two PTL, NOS were @entity404 + and negative for both @entity13433 and perforin. Although the remaining controls expressed @entity13433 and perforin, in keeping with their cytotoxic T or natural killer (NK) cell origin, histological and other immunophenotypical features allowed distinction from SCPTCL. Five cases of SCPTCL were also stained for apoptosis using a tdt-mediated end labeling kit. All cases showed numerous positive apoptotic bodies, suggesting apoptosis as the mechanism of cell death in these @entity5 . Our study indicates that SCPTCL constitutes a distinctive clinicopathological entity derived from cytotoxic T lymphocytes and should be differentiated from other benign and malignant lymphoid infiltrates involving the subcutis. The apoptosis seen in these @entity5 may be mediated by release of cytotoxic granular proteins.

Subcutaneous @entity784 is a XXXX of cytotoxic T lymphocytes.

@entity404 :: ('920', 'Gene') :: ['CD4'] @entity2940 :: ('4684', 'Gene') :: ['CD56'] @entity706 :: ('MESH:D008223', 'Disease') :: ['lymphoma'] @entity5 :: ('MESH:D009369', 'Disease') :: ['tumors'] @entity784 :: ('MESH:D016399', 'Disease') :: ['T cell lymphoma', 'panniculitic T cell lymphoma'] @entity13433 :: ('7072', 'Gene') :: ['T cell intracellular antigen-1', 'TIA-1'] @entity5823 :: ('943', 'Gene') :: ['CD30'] @entity2108 :: ('MESH:D017728', 'Disease') :: ['ALCL', 'anaplastic large cell lymphomas'] @entity3139 :: ('MESH:D015434', 'Disease') :: ['panniculitis'] @entity405 :: ('925', 'Gene') :: ['CD8']
@entity5 :: (MESH:D009369,Disease) :: ['tumor']
