Derm SAQs ·
Lymphoid and histiocytic infiltrates — SAQ
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Stem
A 58-year-old man has a 4-year history of slowly expanding scaly patches on the buttocks and flanks, treated as eczema. New indurated plaques appear. Biopsy shows band-like epidermotropic atypical lymphocytes. Separately, a 9-month-old infant presents with erosive flexural eruption, purpuric scalp papules, and polyuria. Skin biopsy shows coffee-bean histiocytes positive for CD1a and langerin.
Questions
a) Name the most likely diagnosis in the adult and list three histologic/IHC features that support cutaneous T-cell lymphoma of mycosis fungoides type. (3 marks)
b) How would you distinguish cutaneous pseudolymphoma from true lymphoma in a nodular dermal B-cell-rich infiltrate? (2 marks)
c) For the infant, what is the diagnosis suggested by the immunophenotype, and which organ systems must be staged urgently? (3 marks)
d) State one indolent and one aggressive primary cutaneous B-cell lymphoma entity from the WHO-EORTC classification. (2 marks)