Activation of Mast Cells within a Tumor of Angiosarcoma: Ultrastructural Study of Five Cases

Abstract

The accumulation of mast cells around tumors is a well-recognized phenomenon in a number of malignancies, including basal cell carcinoma, melanoma, and breast cancer. However, little information exists regarding mast cells within tumor nests. To clarify the role of mast cells infiltrating in skin cancers, we examined the morphological features of mast cells within tumors of five cases of angiosarcoma, including two patients with Stewart-Treves syndrome, by electron microscopy. In light microscopy, mast cells were observed within tumor nests at various densities and exhibited weak staining intensity with toluidine blue. By electron microscopy, most of the tumor-infiltrating mast cells exhibited anaphylactic or piecemeal degranulation, indicating that the mast cells had been activated in situ. Some mast cells were noted in close apposition to tumor cells, suggesting the existence of direct cell-to-cell interactions. Tumor cells adjacent to mast cells showed no degenerative changes. In conclusion, these results suggest that careful histologic examination in combination with electron microscopy should enable us to identify more mast cells within cancer lesions with greater sensitivity than in a number of prior reports. Furthermore, the close proximity of mast cells and surrounding tumor cells suggests some biologically significant role of mast cells in the development of angiosarcoma, including tumor growth as well as host immunity and stromal reaction.

Mast cells in cutaneous tumors: innocent bystander or maestro conductor?

“…Although a positive correlation between mast cell numbers and microvascular density was found in one study, 12 others have noted an increase of mast cell numbers in the involuting phase of hemangiomas. 13 Accumulation of large numbers of mast cells both within tumor nests 14 and at the periphery of angiosarcomas 15 have also been reported. Perhaps the ability of mast cells to produce angiogenic factors explains their preponderance of mast cells in many vascular neoplasms.…”

Acceleration of tumor growth and peri‐tumoral blood clotting by imatinib mesylate (Gleevec™)

“…Specifically, we contend that imatinib mesylate inhibited the mast cells that naturally infiltrated the tumor, thereby resulting in a reduction of heparin‐mediated anticoagulation within the tumor. Mast cells have been shown to infiltrate breast cancer and many other tumors 4, 5, 18, 19, 20, 21. They have been implicated in promoting tumor metastasis20, 22 and angiogenesis22, 23, 24, 25 and are thought to be associated with a poor prognosis 24, 25.…”

Symplastic hemangioma: report of two cases

“…Previously described cases show bizarre cytologic changes in the background of a cirsoid aneurysm (arteriovenous hemangioma) or capillary‐type hemangioma. Since its original description, a further three cases were reported in the German literature by Kutzner et al 2 Histologically similar vascular lesions with pleomorphic stromal cells probably representing further examples of SH 3 have been described as pleomorphic angioleiomyoma 4–7 cutaneous angiomyolipoma with pleomorphic changes 8 and bizarre angiomyomas of soft tissue 9 . Herein, we describe an additional two cases of this distinctive but poorly recognized entity.…”