RENAL ANGIOMYOLIPOMA - DNA CONTENT AND IMMUNOHISTOCHEMICAL STUDY OF CLASSIC AND MULTICENTRIC VARIANTS

Angiomyolipomas (AMLs) are polymorphic renal tumors that are composed of mature tissues and frequently associated with tuberous sclerosis; A MLs have long been considered hamartomatous in nature. We report the r outine histologic and immunohistochemical features and DNA content ana lysis of two fatal cases of renal giant multicentric AML with distant organ involvement, and we contrast the findings with those of four sim ilarly studied cases of classic solitary AML. Severe nuclear pleomorph ism, significant mitotic activity, and necrosis, which are all charact eristics of multicentric AML, were not seen in the cases of classic AM L. Quantitation of DNA by image analysis of Feulgen-stained slides fro m paraffin-embedded blocks revealed an aneuploid pattern in the two ca ses of multicentric AML and an aneuploid pattern in one of the four ca ses of classic AML. Tumors in the liver, spleen, and lungs in one of t he cases of multicentric AML were diploid. Immunohistochemical analysi s revealed positive staining reaction of vascular and adipose tissue c omponents with HMB-45 antibody in three of the six cases of AML. We co nclude that AMLs may occur in a sarcomatous, infiltrating multicentric form involving multiple organs, that aneuploidy may be seen in lesion s of both the multicentric AML and classic AML variants, that AMLs may feature DNA ploidy heterogeneity in multiple-organ sites, that HMB-45 immunoreactivity may be encountered in AMLs without evidence of nevom elanocytic differentiation, and that continued study of AMLs is needed to clarify further the histogenesis, lineage, clonality, and malignan t potential of these tumors.