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Our purpose was to evaluate the interobserver concordance for the diagnoses of mycosis fungoides (MF), atypical dermatoses (AD), and benign dermatoses (BD) and the impact of T-cell immunophenotyping on the diagnoses MF, AD, and BD. Specimens of MF (n = 57), AD (n = 27), BD and normal skin (n = 54) were reviewed by 2 hematopathologists and 1 dermatopathologist to establish diagnostic interobserver concordance by routine morphologic examination. Immunophenotyping was performed to evaluate expression of CD2, CD3, CD4, CD5, CD7, CD8, CD20, CD30, and MIB-1. The interobserver concordance was fair to moderate compared with the original diagnosis. Partial deletion of CD2 alone was associated significantly with MF. Epidermal deletions of 2 or 3 T-cell antigens or 2 T-cell antigens not including CD7 were associated significantly with MF. An elevated CD4/CD8 ratio correlated with MF. Morphologic features were most diagnostic of MF. Immunophenotyping generally resulted in downgrading of the reaction pattern but was helpful in distinguishing MF from benign dermatoses.

T-cell large granular lymphocyte (T-LGL) leukemias represent monoclonal T-cell expansions that express CD16, CD56, or CD57 and cause cytopenias. The identification of T-LGL leukemias can be difficult because reactive T-LGL cells also can express CD16, CD56, and CD57, and many leukemia cases show only mild lymphocytoses. In this study, 23 T-LGL leukemia cases were analyzed by 3- and 4-color flow cytometry to identify markers that could aid in discriminating leukemic from normal T-LGL. In most cases (18/23), abnormalities (bright, dim, or negative expression) of 2 or more pan-T-cell antigens were identified, with all cases showing abnormal CD5 levels. Abnormal expression of CD94 was identified in 22 of 23 cases, and 15 of 21 cases also showed abnormal expression of class 1 MHC receptor molecules identified by antibodies against CD158a, CD158b, CD158e, CD158i, CD158k, and CD94. These studies help define abnormal phenotypic features typical of T-LGL leukemia that may have important diagnostic value.

T-cell large granular lymphocyte (T-LGL) leukemias represent monoclonal T-cell expansions that express CD16, CD56, or CD57 and cause cytopenias. The identification of T-LGL leukemias can be difficult because reactive T-LGL cells also can express CD16, CD56, and CD57, and many leukemia cases show only mild lymphocytoses. In this study, 23 T-LGL leukemia cases were analyzed by 3- and 4-color flow cytometry to identify markers that could aid in discriminating leukemic from normal T-LGL. In most cases (18/23), abnormalities (bright, dim, or negative expression) of 2 or more pan-T-cell antigens were identified, with all cases showing abnormal CD5 levels. Abnormal expression of CD94 was identified in 22 of 23 cases, and 15 of 21 cases also showed abnormal expression of class 1 MHC receptor molecules identified by antibodies against CD158a, CD158b, CD158e, CD158i, CD158k, and CD94. These studies help define abnormal phenotypic features typical of T-LGL leukemia that may have important diagnostic value.

Posttransplantation lymphoproliferative disorder (PTLD) is a serious complication seen in transplant patients as a consequence of immunosuppressant therapy. Most cases are of B-cell origin and are commonly associated with Epstein-Barr virus (EBV) infection. T-cell PTLDs are rare and only 13 pediatric T-cell PTLDs with clinicopathologic correlation have been reported previously. We present the histologic, immunophenotypic, and molecular features of a monomorphic PTLD (T-cell lymphoma) identified in a pediatric patient following orthotopic liver transplantation. The lymphoma was identified in the ileum, rectum, and mesenteric lymph nodes. In situ hybridization revealed numerous EBER-1-positive tumor cells. A current review of the literature is also discussed. Of the 14 cases of pediatric T-cell PTLD reported in the literature, only 3 (21.4%) are described as being EBV positive. Most of the reported PTLDs are monoclonal, with 9 of 11 cases (82%) showing a clonal T-cell population by gene rearrangement studies. T-cell PTLD cases appear to have a poor prognosis (11 of 14 patients died of the disease), although patients with involvement of specific anatomic sites may have a better outcome.

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5 Osborne J, Hutchinson P. A follow-up study to investigate the efficacy of initial treatment of lentigo maligna with surgical excision. Br J Plast Surg 2002; 55:611-15. 6 Zalaudek I, Horn M, Richtig E. Local recurrence in melanoma in situ: influence of sex, age, site of involvement and therapeutic modalities. Br J Dermatol 2003; 148:703-8. 7 O'Donnell B, Dervan P, Codd M et al. A clinicopathological correlation of 134 stage 1 and 79 non-invasive cutaneous melanomas presenting over a decade (1984-93) at the Mater Misericordiae Hospital, Dublin. Ir J Med Sci 1998; 167:132-5. 8 Somach SC, Taira JW, Pitha JV et al. Pigmented lesions in actinically damaged skin. Histopathologic comparison of biopsy and excisional specimens. Arch Dermatol 1996; 132:1297-302. 9 Witheiler DD, Cockerell CJ. Sensitivity of diagnosis of malignant melanoma: a clinicopathologic study with a critical assessment of biopsy techniques.

Our purpose was to evaluate the interobserver concordance for the diagnoses of mycosis fungoides (MF), atypical dermatoses (AD), and benign dermatoses (BD) and the impact of T-cell immunophenotyping on the diagnoses MF, AD, and BD. Specimens of MF (n = 57), AD (n = 27), BD and normal skin (n = 54) were reviewed by 2 hematopathologists and 1 dermatopathologist to establish diagnostic interobserver concordance by routine morphologic examination. Immunophenotyping was performed to evaluate expression of CD2, CD3, CD4, CD5, CD7, CD8, CD20, CD30, and MIB-1. The interobserver concordance was fair to moderate compared with the original diagnosis. Partial deletion of CD2 alone was associated significantly with MF. Epidermal deletions of 2 or 3 T-cell antigens or 2 T-cell antigens not including CD7 were associated significantly with MF. An elevated CD4/CD8 ratio correlated with MF. Morphologic features were most diagnostic of MF. Immunophenotyping generally resulted in downgrading of the reaction pattern but was helpful in distinguishing MF from benign dermatoses.