Extramedullary Hematopoiesis: An Unusual Finding in Angiolymphoid Hyperplasia With Eosinophilia.Am J Dermatopathol 2019; 41(9):680-683AJ
Extramedullary hematopoiesis is the process of blood cell synthesis occurring outside the medulla of the bone marrow. During fetal development, extramedullary hematopoiesis is considered physiological; however, it is considered pathologic when occurring outside the neonatal period. Angiolymphoid hyperplasia with eosinophilia (ALHE) describes a lesion characterized histologically by plump endothelial cells associated with a mixed inflammatory infiltrate of lymphocytes, plasma cells, mast cells, and eosinophils. This report describes an adolescent boy with an isolated preauricular facial lesion. After excision, histopathology confirmed a diagnosis of ALHE with the additional finding of trilineage extramedullary hematopoiesis. To the authors' knowledge, this is the first reported case of extramedullary hematopoiesis in ALHE.