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Case History

65-year-old man with 8 cm mass involving skin of right shoulder (A). High power of dermis (B). High power of subcutaneous tissue (C). Immunostains of dermal infiltrate (D). Immnuostains of subcutaneous infiltrate (E). Flow of marrow and blood: few CD5+ monoclonal B cells.

What is the diagnosis?

  1.       SLL with Richter's
  2. BPDCN
  3.       Myeloid sarcoma + SLL
  4.       BPDCN + SLL



 Answer:  C. Myeloid sarcoma+SLL


The skin shows involvement by both myeloid sarcoma (dermis) and small lymphocytic lymphoma (SLL).

Myeloid sarcoma is a tumor mass consisting of myeloid blasts, with or without maturation, occurring at an anatomical site other than the bone marrow. On immunohistochemistry in paraffin sections, tumors with a more immature myeloid profile express CD33, CD34, and KIT (CD117). Staining for TdT, MPO, and CD45 is inconsistent.

Chronic lymphocytic leukaemia/small lymphocytic lymphoma (CLL/SLL) is a neoplasm composed of monomorphic small mature B cells that coexpress CD5 and CD23. Extranodal involvement

(e.g. of the skin, gastrointestinal tract, or CNS) occurs in a small subset of cases.

Source: Swerdlow, S. H. (Ed.). (2017). WHO classification of tumours of haematopoietic and lymphoid tissues. International Agency for Research on Cancer.

Case contributed by: Diana Morlote, M.D., Assistant Professor, Genomic Diagnostics and Bioinformatics