Bone Marrow Invovlement by NK/T Cell Lymphoma

Lessons From the Friday Unknowns

The patient has a history of extranodal NK/T cell lymphoma, nasal type.

Histologic sections show a fragment of bone marrow with focally increased cellularity, reaching up to 80% in some areas, with trilineage hematopoiesis.

The bone marrow is focally invovled by a neoplastic lymphocytic infiltrate composed of medium-sized to large lymphocytes with irregular nuclear contours, some with perinuclear halos, fine chromatin and prominent nucleoli.

Immunohistochemical stains for CD3, CD4, CD5, CD8, CD20, and CD56 are performed. CD20 stains rare B-cells. CD3 and CD5 stain scattered interstitial mostly small lymphocytes and show largely similar staining pattern.

CD56 stains rare scattered larger lymphoid cells, which appear positive for granzyme B. EBER in situ hybridization is positive in rare scattered larger lymphoid cells and shows similar distribution to that of CD56 stain.

EBER stain

Link to digital slides: | Slides labeled case 3



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Siba El Hussein, MD

Siba El Hussein, MD

Hematopathology | Cytopathology | Molecular pathology | Digital pathology | Data science | Machine learning