Morphologically occult systemic mastocytosis in bone marrow: Clinicopathologic features and an algorithmic approach to diagnosis

Kaaren K. Reichard, Dong Chen, Animesh Pardanani, Rebecca F. McClure, Matthew T. Howard, Paul J. Kurtin, Adam J. Wood, Rhett P. Ketterling, Rebecca L. King, Rong He, William G. Morice, Curtis A. Hanson

Research output: Contribution to journalArticlepeer-review

8 Scopus citations


Objectives: Bone marrow (BM) biopsy specimens involved by systemic mastocytosis (SM) typically show multifocal, compact, dense aggregates of spindled mast cells (MCs). However, some cases lack aggregate formation and fulfill the World Health Organization 2008 criteria for SM, based on minor criteria. Methods: We identified 26 BM cases of KIT D816V- mutated, morphologically occult SM in the BM. Results: All patients had some combination of allergic/ MC activating symptoms. Peripheral blood counts were generally normal. BM aspirates showed 5% or less MCs, which were only occasionally spindled. BM biopsy specimens showed no morphologic classic MC lesions. Tryptase immunohistochemistry (IHC) demonstrated interstitial, individually distributed MCs (up to 5%) with prominent spindling, lacking aggregate formation. MCs coexpressed CD25 by IHC and/or flow cytometry. Spindled MCs constituted more than 25% of total MCs in all cases and more than 50% in 20 of 26 cases. Conclusions: Morphologically occult involvement of normal-appearing BM by SM will be missed without appropriate clinical suspicion and pathologic evaluation by tryptase and CD25 IHC and KIT D816V mutation analysis. On the basis of these findings, we propose a cost-effective, data-driven, evidence-based algorithmic approach to the workup of these cases.

Original languageEnglish (US)
Pages (from-to)493-502
Number of pages10
JournalAmerican journal of clinical pathology
Issue number3
StatePublished - Sep 2015


  • Algorithm
  • Evidence-based medicine
  • KIT D816V
  • Mast cell activation
  • Mastocytosis
  • Test utilization

ASJC Scopus subject areas

  • Pathology and Forensic Medicine


Dive into the research topics of 'Morphologically occult systemic mastocytosis in bone marrow: Clinicopathologic features and an algorithmic approach to diagnosis'. Together they form a unique fingerprint.

Cite this