Hematopathology — Image #43 — Anaplastic Large Cell Lymphoma

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At low power anaplastic large cell lymphoma may resemble Hodgkin lymphoma or carcinoma given the profusion of large cells. Cells with a horseshoe-shaped nucleus are often found in this neoplasm. The cells are reactive for T-cell antigens, most often CD-2 and CD-4, and show reactivity for CD-30. In contrast to Hodgkin lymphoma, the cells do not show reactivity for CD-15. Most cases present in childhood with extensive nodal and extranodal involvement. Most of these cases will show expression of ALK protein (a tyrosine kinase) associated with t(2;5). This is a good prognostic sign. In contrast, adults usually present with disease localized to the skin with no expression of ALK protein and a poor prognosis.

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