An evaluation of immunohistologic stains for immunoglobulin light chains in bone marrow biopsies in benign and malignant plasma cell proliferations.

Bone marrow specimens from 226 patients with a variety of benign and malignant plasma cell proliferations were studied to assess the reliability of immunohistologic studies in their evaluation. The clonality of the bone marrow plasma cells was compared with results of serum and urine electrophoreses. Discordance was observed most frequently in cases in which a paraprotein was demonstrated, but no monoclonality was detected by immunoperoxidase (16 cases). Of these 16 cases, 9 had 5% or less bone marrow plasma cells. In only one case was the light chain class of the bone marrow plasma cells different from that of the paraprotein. If discordant cases with 5% or less plasma cells are eliminated, the overall concordance was 97%. The authors' findings indicate that immunohistologic studies for immunoglobulin light chains in Zenker-fixed decalcified bone marrow biopsy sections are reliable in the evaluation of patients with plasma cell proliferations when the marrow contains more than 5% plasma cells.

The histologic features of hyperplastic lymphadenopathy in AIDS-related complex are nonspecific.

Follicular hyperplasia is the most common histologic finding in lymph nodes of patients with AIDS-related complex (ARC) and persistent generalized lymphadenopathy. To determine the specificity of the published features considered characteristic of this condition, we compared two sets of lymph-node biopsy specimens with follicular hyperplasia. Thirty-eight specimens were from human immunodeficiency virus (HIV/HTLV3/LAV) positive homosexual men with persistent generalized lymphadenopathy, and 87 specimens were from patients free of AIDS risk. Polykaryocytes, epithelioid histiocytes, and follicle mantle zone effacement were significantly more common in the ARC group. Dermatopathic change and so-called follicle lysis were significantly more common in control, non-ARC nodes. No statistically significant difference between the two groups could be demonstrated for the following features: irregularity of follicles, burnt-out follicles, sinus monocytoid cells, marked plasmacytosis, and the toxoplasmosis triad. Most importantly, no feature was seen exclusively in either of the two groups. Although some features considered characteristic of the hyperplastic form of ARC lymphadenopathy are seen more commonly in this condition than in lymph nodes showing follicular hyperplasia unrelated to ARC, none of these features is specific for ARC and there is no histologic picture diagnostic of this condition.