Splenic para-amyloid material: a possible vasculopathy of the acquired immunodeficiency syndrome.

We have observed perivascular para-amyloid in the spleens of acquired immune deficiency syndrome (AIDS) patients at autopsy. Whether this phenomenon is unique to AIDS patients or is a common degenerative phenomenon in the spleen has not been determined. Autopsy spleens from 355 patients (171 AIDS, 184 non-AIDS) were graded for presence of splenic para-amyloid material (SPAM) on a scale of 0 to 3. The average ages of the AIDS and non-AIDS groups were 38.4 and 60.4 years, respectively. All SPAM-positive AIDS cases had age-matched non-AIDS controls. Selected positive cases were examined ultrastructurally. Of the 171 AIDS patients, 55 had SPAM; in 30 cases, it was considered grade 2 or 3. Although none of the non-AIDS cases were graded 2 or 3, eight of them were grade 1. SPAM is highly correlated with AIDS (32.1 v 4.3%; P < .0001), with a specificity of 95.6% and a positive predictive value of 87.3%. These perivascular deposits correspond to areas of periarteriolar lymphoid sheaths and appear to be in continuity with arteriolar adventitia. Ultrastructurally, they contain collagen, long-spaced collagen, fibrillin, and occasional residual cells. No viral particles were noted. SPAM appears to be more prevalent and in greater quantity in AIDS patients. It does not correlate with advanced age; it can be mistaken for amyloid. Its consistent association with the adventitia of vessels raises the possibility of a new vasculopathy of AIDS; it also may be related to follicular involution and hyalinization associated with regression of prior follicular hyperplasia.