13 July 2026
: Case report 
Coexistence of Multiple Myeloma, Mast Cell Hyperplasia, and Low-Level Myeloid Blastocytosis: A Report of a Rare Case
Challenging differential diagnosis, Unusual or unexpected effect of treatment, Diagnostic / therapeutic accidents, Rare disease
Meng Yang BEF 1, Qian Wang D 1, Jian Zhang D 1, Hong Jiang E 1, Hongzhi Xu A 1, Kang Lu G 1, Yujie Jiang AG 1*DOI: 10.12659/AJCR.952005
Am J Case Rep 2026; 27:e952005
Table 3 Comparison of the patient’s features to the SM diagnostic criteria. WHO diagnostic criteria for SM: if a diagnosis of SM is made, at least 1 major and 1 minor or 3 minor criteria should be fulfilled.
| Diagnostic criteria | Systemic mastocytosis (SM) | Patient |
|---|---|---|
| Major criterion | ≥15 mast cells in multifocal dense infiltrates in bone marrow biopsies and/or in sections of other extracutaneous organs | A single mast cell aggregate with >15 cells in bone marrow biopsies |
| Minor criteria | (1) ≥25% of all mast cells are spindle-shaped | (1) 10% oval-shaped mast cells |
| (2) KIT-activating at codon 816 or in other critical regions | (2) KIT D816V mutation negative. Other KIT mutations were not tested | |
| (3) Mast cells express one or more of: CD2 and/or CD25 and/or CD30 | (3) CD117 positive, CD2 and CD30 negative. CD25 was not tested | |
| (4) Baseline serum tryptase concentration >20 ng/mL | (4) Baseline serum tryptase concentration 19.1 ng/mL | |
| The diagnosis of SM requires meeting either the major criterion and at least 1 minor criterion, or at least 3 minor criteria concurrently. | ||