Fibrous long-spacing (FLS)
collagen is a distinct ultrastructural form of
collagen present in normal tissue, various
tumors, and tissues degraded by bacterial
collagenases in vivo and in vitro. An association between FLS
collagen and
bacillary angiomatosis has not been previously described. Six cases of
bacillary angiomatosis, including one autopsy case with disseminated disease, were examined ultrastructurally. In addition,
Kaposi sarcoma (3),
pyogenic granuloma (3),
capillary hemangioma (3), and
cavernous hemangioma (2) were examined for comparison. A vascular proliferation in a lymph node from a patient with
AIDS (1) and a case of pulmonary capillary hemangiomatosis (1), also in an
AIDS patient, were studied. Abundant FLS
collagen was identified in 4 of 6 cases of
bacillary angiomatosis, in close association with the organisms. FLS
collagen was not seen beyond the immediate vicinity of the organisms. The FLS
collagen in
bacillary angiomatosis was seen in skin biopsies and in lung and skeletal muscle in the autopsy case; in the latter case, as well as in the two
AIDS-associated, nonbacillary
angiomatosis, non-
Kaposi sarcoma vascular proliferations, there was a striking distribution of FLS
collagen around small blood vessels. Occasional FLS
collagen was observed in all three
pyogenic granuloma. When present in
pyogenic granuloma, FLS
collagen was intermixed with subendothelial
collagen. Abundant FLS
collagen was identified in close association with the organisms of
bacillary angiomatosis in four cases; this morphologic alteration was seen in skin as well as lung and skeletal muscle. An association between FLS
collagen and endothelial cells in normal tissue (Descemet's membrane) and in certain vascular proliferations appears to exist.