Clinicopathologic characterization of cutaneous adult T-cell leukemia/lymphoma: A single tertiary care center experience in the United States.

OBJECTIVES: Adult T-cell leukemia/lymphoma (ATLL) is a rare aggressive T-cell leukemia/lymphoma associated with human T lymphotropic virus type 1 infection. The patients might present with skin rash before, at, or after the diagnosis. The dermatopathologic finding might be diagnostically very challenging. METHODS: We retrospectively identified 110 patients with ATLL at a single institution in a 19-year period, with 19 patients having skin biopsies. Clinical, dermatopathologic, immunophenotypic, and molecular findings were studied. RESULTS: The cohort included 13 skin-first (5 acute, 5 lymphomatous, 2 chronic, 1 smoldering), 6 skin-second (4 acute, 1 lymphomatous, 1 smoldering), and 91 patients without skin biopsy. Some nonphotoprotected areas of body such as the forearm and lower lip were also seen. Skin manifestations included papular (5), erythroderma (1), nodulotumoral (3), plaques (1), patches (1), and a combination of skin rashes (2). Histopathologic findings included large pleomorphic cells, angiocentrism, epidermal infiltration with large Pautrier-like microabscesses, and folliculotropism. Fifteen (78.9%) cases showed CD4+/CD7-/CD25+. Next-generation sequencing study was conducted on 5 patients using either blood or bone marrow samples, revealing multiple genetic mutations across multiple signaling pathways. CONCLUSIONS: Pleomorphic large, atypical cells with CD4+/CD25+/CD7- immunophenotype from a non-"bathing trunk" location, especially in a patient from endemic regions, raise suspicion for ATLL. T-cell receptor gene rearrangement is almost always positive, and the neoplasm usually demonstrates multiple mutations by next-generation sequencing study.

CD138- Plasmablastic Lymphoma: A Multi-institutional Study and Review of the Literature.

CONTEXT.­: Plasmablastic lymphoma (PBL) is a rare aggressive lymphoma, usually positive for CD138 and frequently occurring in the oral cavity of human immunodeficiency virus (HIV) patients. Up to 10% of cases are negative for CD138 and diagnostically very challenging. OBJECTIVE.­: To investigate the appropriate approach to diagnose CD138- plasmablastic lymphoma and avoid misdiagnosis. DESIGN.­: We studied 21 cases of CD138- PBL from multiple large institutes in the United States and 21 cases from the literature. RESULTS.­: CD138- PBLs were positive for different B/plasma cell markers at various percentages: MUM1 (94.4%; 34 of 36), OCT2 (70.6%; 12 of 17), immunoglobulin light chains (68.8%; 22 of 32), CD38 (68.4%; 13 of 19), CD79a (34.2%; 13 of 38), and PAX5 (15.6%; 5 of 32), suggesting that MUM1, OCT2, immunoglobulin light chains, and CD38 are useful markers to help establish the lineage. A total of 83% of cases (30 of 36) were extraoral lesions. Extraoral lesions showed much lower Epstein-Barr virus (EBV) infection rates (16 of 30; 53.3%) and had worse prognosis. MYC was positive in 80% (8 of 10) of EBV+ cases and 40% (2 of 5) EBV- cases, indicating the importance of MYC in pathogenesis, especially in EBV+ cases. CONCLUSIONS.­: Our study emphasizes that CD138- PBLs tend to be extraoral lesions, with much lower EBV infection rates, and diagnostically very challenging. Accurate diagnosis requires a thorough investigation and workup by using appropriate markers.