Cutaneous ALCL

Immunophenotypically, cutaneous ALCL cells are usually CD30-positive and express pan-T cell antigens, most frequently CD2, and are usually CD4-positive. In addition, they usually express CD43 (B9, BIO, K3, W6). In contrast to systemic ALCL, cutaneous ALCL cells less commonly express EMA (C15, K10) cutaneous ALCLs often are positive for cytotoxic cell-associated antigens such as granzyme B, perforin, and TIA-1 (B22, K32). Again in contrast to the systemic ALCL cases, cutaneous ALCL cases are negative for the ALK-1 protein (Table 7) (B16). 

Immunophenotypic Profiles Primary Cutaneous ALCL vs. ALCL vs. NLPHL vs. cHL ... 

MM = multiple myeloma ATL = adult T-cell leukemia ALL = acute lymphoblastic leukemia CLL = chronic lymphocytic leukemia FCC = follicular center cell lymphoma DLC = diffuse large cell lymphoma TRB = T-cell rich B-cell lymphoma ALCL = anaplastic large cell lymphoma MALT = mucosa-associated lymphoid tissue-type lymphoma LC = lung cancer CMM = cutaneous malignant melanoma TCC = transitional cell carcinoma CSCC = cutaneous squamous cell carcinoma. 

In contrast to RAH/ALCL, lymphomatoid papulosis (LYP) follows a more consistently indolent course, and, as such, it is still not uniformly accepted as a malignant disease. LYP may arise in virtually any cutaneous or mucocutaneous surface, although axial sites are most common. The typical lesions are small papules that may undergo central hemorrhage and necrosis before healing... 

More than 40% of all variants of ALCL are associated vdth the reciprocal t(2 5)(p23 q35) translocation, which is associated with more than 80% of pediatric and with one-third of adult ALCL. This translocation found to be the most common cytogenetic abnormality in non-cutaneous form of this lymphoma. Further, but less common chromosomal abnormalities described in association with ALCL are the translocations t(2 3)(p23 q21), t(l 2)(q25 p23), inv.(2)(p23 q35), t(2 13)(p23 q34), t(X 2) (qll-12 p23), t(2 17)(p23 qll) and t(2 19)(p23 pl3). All of these translocations involve the ALK gene on chromosome 2 and seems to have a similar pathophysiological mechanism. 

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