LAUSR

IMAGE 1 Peripheral blood film shows circulating mast cells. Both “normal” and “atypical” circulating mast cells were noted. Atypical features included hypogranular spindled cytoplasms and eccentric nuclei (panel A, Wright-Giemsa stain 20 magnification). Panel B shows a hypercellular bone marrow biopsy and a large mast cell infiltrate that occupies a large portion of the biopsy (approximately 70%, panel B, trephine biopsy 10 magnification). In the cellular portions of the biopsy, eosinophilic and megakaryocytic hyperplasia are evident (trephine biopsy, panel C, 50 magnification). Mast cells were stained by tryptase, CD117 and CD25 but not CD2 (panels D–G 4 with inset 20 magnification, respectively). Reticulin fibrosis and deposition of collagen was present in this specimen (panel H, reticulin stain showing MF 3/3, and trichrome stain, panel I, 4 with inset 20 magnification, respectively) Received: 8 February 2022 Accepted: 15 February 2022