Anaplastic large cell lymphoma, ALK+ Clinical • First 3 decades of life, M>F • Often nodal + extranodal sites (MC are skin, bone, soft tissue, lungs, liver) • BM involvement often subtle • Small cell variant can have leukemic presentation • Some isolated skin - may be indolent • Most present w advanced stage + B symptoms Histology • Variable number of cells w horseshoe- or kidney-shaped nuclei, sometimes w eosinophilic hof (Hallmark cells) • Donut cells (nuclear pseudoinclusions) • Multinucleated cells, wreath-like • Nucleoli can be seen but are usually not eosinophilic/inclusion-like • May grow in LN sinuses and resemble metastatic tumor • Lymphohistiocytic pattern: mixed w reactive histiocytes, neoplastic cells often around vessels • Small cell pattern: small to medium w irregular nuclei, sometimes fried-egg morphology, but still has hallmark cells around vessels • Hodgkin-like pattern: mimics NS CHL • Composite pattern: more than one • Rare cases are hypocellular/spindled Dr. Laura Brown @lauraebrown #Anaplastic #largecell #lymphoma #ALKPos #hemepath #pathology
