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Delineation of Patterns of Bone Marrow Mast Cell Infiltration in Systemic Mastocytosis
Value of CD25, Correlation With Subvariants of the Disease, and Separation From Mast Cell Hyperplasia

Manuela Krokowski MD, Karl Sotlar MD, Maria-Theresa Krauth MD, Manuela Födinger MD, Peter Valent MD, Hans-Peter Horny MD
DOI: http://dx.doi.org/10.1309/CX45R79PCU9HCV6V 560-568 First published online: 1 October 2005


In most cases, the diagnosis of systemic mastocytosis (SM) is based on histomorphologic evaluation of the bone marrow. We analyzed mast cell (MC) infiltration patterns in 57 cases of SM and 31 cases of mast cell hyperplasia (MCH). Tryptase immunohistochemical analysis was used for MC detection and CD25 to distinguish neoplastic from normal MCs. The following infiltration patterns were found: I, diffuse interstitial; II, focal, dense; III, focal, dense with an additional diffuse component, located preferentially around focal infiltrates; IV, focal, dense with an additional diffuse component evenly distributed throughout; and V, diffuse, dense. In 29 cases of MCH, MCs formed the type I pattern. The majority of SM cases exhibited patterns II to V; type IV was the most frequent (n = 36). Type V was seen in 3 cases of MC leukemia and 1 case of smoldering SM. In 1 case of SM, type I infiltration was found; the SM diagnosis was based on 3 minor SM criteria. Our data show that the infiltration pattern in SM correlates with the disease subtype and should be recognized as an important aspect in the histomorphologic evaluation of the bone marrow.

Key Words:
  • Mast cell
  • Mastocytosis
  • Bone marrow, Tryptase
  • CD25
  • c-kit