title: Pigmented Epithelioid Angiomyolipoma of the Kidney.
abstract: Extensive melanin pigment in an epithelioid angiomyolipoma, a potentially malignant and locally aggressive renal tumor, has been rarely reported. A 53-year-old, asymptomatic man with no significant past medical history underwent partial nephrectomy for a right kidney mass discovered on CT scan. Grossly, the mass was 4 cm, well-circumscribed, dark, brown-black. Microscopically, nests of large, clear-to-eosinophilic cells with mildly atypical, vesicular nuclei and prominent nucleoli were separated by striking vascular network. Abundant, brown-black, coarsely granular pigment was noted. The tumor stained with HMB-45 and MART-1 and was negative for broad spectrum cytokeratin, CK-7, CD-10, RCC antigen, EMA, vimentin, SMA, desmin, synaptophysin, chromogranin, and S 100. Fontana-Masson stain confirmed presence of melanin. Thick-walled vessels, spindle cells, and fat were absent. The patient had no family history of tuberous sclerosis. Close follow-up was recommended. It is important to differentiate this entity from melanoma, pigmented renal cell carcinoma, and pigmented paraganglioma.
authors.forename: Raveena
authors.initials: R
authors.lastname: Reddy
authors.forename: Jack R
authors.initials: JR
authors.lastname: Lewin
authors.forename: Veena
authors.initials: V
authors.lastname: Shenoy
mesh_terms: D018207:Angiomyolipoma / Q000175:diagnosis* / Q000473:pathology / Q000601:surgery; D002292:Carcinoma, Renal Cell / Q000175:diagnosis; D006801:Humans; D007680:Kidney Neoplasms / Q000175:diagnosis* / Q000473:pathology / Q000601:surgery; D008297:Male; D008545:Melanoma / Q000175:diagnosis; D008875:Middle Aged; D009392:Nephrectomy / Q000379:methods*; D010235:Paraganglioma / Q000175:diagnosis; D012835:Silver Nitrate; D014057:Tomography, X-Ray Computed
chemical_list: C051037:Fontana-Masson stain; D012835:Silver Nitrate