Mast cell changes in skin diseases

Ultrastructure of cerebellar capillary hemangioblastoma. II. Mast cells and angiogenesis

The topographic distribution, population density, and ultrastructural features of mast cells were studied in six cases of cerebellar capillary hemangioblastoma. The vascular area of tumor tissue contained large numbers of mast cells (6.3 cells/high power field, X 400) in comparison with hyalinized area (0.3 cell) and adjacent cerebellar tissue (less than 0.1 cell). Close association of mast cells with endothelial cells and stromal cells was found. The morphology of mast cell granules and their degranulation through dissolution of granule contents and exocytosis were illustrated. The findings suggest that an increased number of mast cells may represent one of the characteristic histological features of capillary hemangioblastoma, and continuous degranulation of mast cell granules with release of heparin may play an important pathophysiologic role in the vascular proliferation and expansion of the tumor.

Ultrastructure of mast cells in growing and involuting stages of hemangiomas

Mast cells from 11 patients with growing strawberry (capillary) hemangiomas and cellular hemangiomas and from ten patients with involuting stages of strawberry hemangiomas were investigated electron microscopically. Two types of mast cells were evident: numerous elongated, fibroblastic cells and a few round, classic cells. The mast cells in growing hemangiomas contained many small, simple-type granules in various stages of development. It is possible that, owing to the immaturity of these granules, mast cells have different, probably weaker, functional activities. Mast cells in involuting stages of hemangiomas were filled primarily with compound-type granules, showing typical parallel, concentric lamellae or crystalloid structures, which were similar to the mature mast cells in normal skin.