Oral lichen sclerosus expressing extracellular matrix proteins and IgG4-positive plasma cells.

Lichen sclerosus (LS) is a mucocutaneous disease with uncommon oral involvement. The etiology is not yet well understood, but LS has been associated with autoimmune, genetic, and immunological factors. We report a 47-year-old man with LS that exhibited an asymptomatic white plaque with red patches on the maxillary alveolar mucosa extending to the labial mucosa. He had no other skin disease. Positive immunostaining for tenascin and scarcity of fibronectin suggested extracellular matrix reorganization. Elastin immunostaining indicated a reduction of elastic fibers. Immunoexpression of collagen IV in blood vessels and its absence in the epithelial basement membrane, together with diffuse MMP-9 immunoexpression, suggested altered proteolytic activity. Mast cell staining bordering areas of sclerosis indicated a possible role in the synthesis of collagen. IgG4 positivity in plasma cells suggested a role in the fibrogenesis. This is an unusual presentation of oral LS and we discuss immunohistochemical findings regarding cellular and extracellular matrix components.

Distinctive renal cell tumor simulating atrophic kidney with 2 types of microcalcifications. Report of 3 cases.

We report 3 cases of primary renal cell tumor simulating atrophic kidney with distinct gross, morphologic, immunohistochemical, and molecular genetic features. The tumors were retrieved out of more than 17 000 renal tumors from the Plzen Tumor Registry. Tissues for light microscopy had been fixed, embedded, and stained with hematoxylin and eosin using routine procedures. The tumors were further analyzed using immunohistochemistry, array comparative genomic hybridization, and human androgen receptor. Analyses of VHL gene and loss of heterozygosity (LOH) 3p were also performed. The patients were 2 women and 1 man, with ages ranging from 29 to 35 years (mean, 31.3 years). Grossly, the neoplasms were encapsulated and round with largest diameter of 3.5 cm (mean, 3.2 cm). Follow-up available for all patients ranged from 2 to 14 years (mean, 8 years). No aggressive behavior was noted. Histologically, akin to atrophic (postpyelonephritic) kidney parenchyma, the tumors were composed of follicles of varying sizes that were filled by eosinophilic secretion. Rare areas contained collapsed follicles. Each follicle was endowed with a small capillary. The stroma was loose, inconspicuous, and focally fibrotic. Two types of calcifications were noted: typical psammoma bodies and amorphous dark-blue stained calcified deposits. Immunohistochemically, tumors were strongly positive for cytokeratins (OSCAR), CD10, and vimentin, with weak immunopositivity for CAM5.2 and AE1-AE3. WT1 and cathepsin K were weakly to moderately focally to diffusely positive. Tumors were negative for cytokeratin 20, carbonic anhydrase IX, parvalbumin, HMB45, TTF1, TFE3, chromogranin A, thyroglobulin, PAX8, and ALK. Only 1 case was suitable for molecular genetic analyses. No mutations were found in the VHL gene; no methylation of VHL promoter was noted. No numerical aberrations were found by array comparative genomic hybridization analysis. LOH for chromosome 3p was not detected. Analysis of clonality (human androgen receptor) revealed the monoclonal nature of the tumor. We describe an unknown tumor of the kidney that (1) resembles renal atrophic kidney or nodular goiter of thyroidal gland; (2) contains a leiomyomatous capsule and 2 types of calcifications; (3) lacks mitoses, atypias, necroses, and hemorrhages and nearly lack Ki-67 positivity; and (4) so far showed benign biological behavior.