Lessons From the Friday Unknowns Histologic sections show lymphoma and fibrosis. In some areas, the neoplasm appears to be nodular and nodules are surrounded by fibrous bands.

Lessons From the Friday Unknowns Histologic sections show a lesion with extensive coagulative necrosis. There is no evidence lymph node in this specimen. The lesion is composed of numerous spindle cells associated with inflammatory cells including lymphocytes, eosinophils and neutrophils, the latter near the areas of necrosis.

Lessons From the Friday Unknowns Sections of intestinal mucosa reveal the presence of a dense lymphocytic infiltrate, comprising small, monomorphic appearing lymphocytes, within intestinal mucosa.

Lessons From the Friday Unknowns Sections of the right inguinal lymph node needle biopsy show a neoplastic lymphocytic infiltrate, comprising predominantly lymphocytes of small and intermediate size, with few scattered atypical large lymphoid cells present. There is admixture of histiocytes in areas of the infiltrate. A prominent vascular proliferation is present.

Lessons From the Friday Unknowns Sections of the lymph node show a mixed population of of lymphoma cells of intermediate and large size that are present in a vaguely nodular pattern, consistent with colonization of pre-existing lymph node follicles. Large lymphoma cells are moderately to markedly increased in areas. …

Lessons From the Friday Unknowns The patient presented with a clinical picture of hemophagocytic lymphohistiocytosis. The patient also has mild thoracic lymphadenopathy. The biopsy specimen is 50–60% cellular. Both specimens show large atypical lymphoma cells in an interstitial distribution. There is also trilineage hematopoiesis and there are many abnormal megakaryocytes that are composed of naked…