|
S13C11P9-3: In this field, distinctive endothelial cells have qualities which have been characterized as “histiocytoid;” the cells have pale,
acidophilic cytoplasm and enlarged, eccentric nuclei; in addition, many of the nuclei are notched, or irregular in outline. This lesion shares some features with reactive processes such as granulation tissue and
pyogenic granuloma. It has been variously characterized as angiolymphoid hyperplasia with eosinophilia and as histiocytoid hemangioma. It has neoplastic qualities but, on the other hand, shares features with
reactive processes; it is a borderline process. Lesions in this category are often associated with infiltrates of lymphocytes, histiocytes, and eosinophils. Some examples are solitary in the soft tissue,
particularly in the subcutaneous tissue. Some examples in the skin, although localized, can be associated with satellite lesions. The solitary, subcutaneous lesions tend to be arranged in zonal patterns. Often there
is an eccentric, muscular, feeder vessel from which the endothelial cords and vessels take their origin. The newly formed vessels are most primitive (i.e., angioblastic forms with cytoplasmic vesicles are
represented) near the site of their origin from a feeder vessel. Near the periphery of such a lesion, the vessels tend to be more mature; they often display the qualities of post-capillary venules (vessels with high
endothelium). The inflammatory infiltrates tend to be most prominent in association with the “mature” vessels of post-capillary type. Vessels of post-capillary type are structured to allow for the egress of
inflammatory cells from the vessels into tissue.
|
