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Background: Neurofibromatosis, type 1, is associated with cutaneous melanin pigmentation, but an association with ordinary melanocytic nevi has not been described., Methods: This retrospective case-control study was designed to see if neurofibromas in patients with neurofibromatosis, type 1 (NF-1) differ from sporadic neurofibromas (SN) in their incidence of associated melanocytic nevi and other histologic features. Slides from 114 NF-1 were compared with 112 SN and 300 intradermal melanocytic nevi (IDN)., Results: Small lentiginous melanocytic nevi were identified over 13 NF-1 (11%) but no SN (P=0.0002). Compared with other NF-1, NF-1 with nevi were more frequently associated with melanocytic hyperplasia, giant melanosomes and diffuse neurofibroma (P<0.03). Compared with SN, NF-1 were also more frequently associated with melanocytic hyperplasia, lentigo simplex-like changes, diffuse neurofibroma and plexiform neurofibroma (P<0.001). Sebaceous hyperplasia (14%), dermal elastosis (9%), lipomatous change (8%), epithelial cysts (4%) and keratin granulomas or folliculitis (3%) were not significantly different in prevalence between NF-1, SN and the control group of IDN., Conclusions: This study suggests that there is a difference in the potential for melanocytic proliferation in NF-1 compared with SN. NF-1, SN and IDN are associated with a similar range of incidental histologic changes. Ball NJ, Kho GT. Melanocytic nevi are associated with neurofibromas in neurofibromatosis, type 1, but not sporadic neurofibromas. A study of 226 cases.

Background: Naked sarcoidal granulomas (NSGs) are the characteristic histologic finding in sarcoidosis. This descriptive study was designed to identify the frequency of other histologic changes in cutaneous sarcoidosis., Methods: The slides from 28 sequential biopsies previously diagnosed as sarcoidosis in patients with known systemic sarcoidosis were reviewed., Results: Classic NSGs were identified in 25 biopsies (89%). Four biopsies contained tuberculoid granulomas, two with neutrophils suggesting infection (cultures negative). Five biopsies contained interstitial granulomas that resembled granuloma annulare and necrobiosis lipoidica in one case each. Additional histologic findings included birefringent foreign material in 14 biopsies (50%), focal necrosis (43%), elastophagocytosis (39%), linear peri-neural granulomas resembling leprosy (25%), increased dermal mucin (18%) and lichenoid inflammation (14%) [two with plasma cells resembling syphilis (7%)]. In all but three cases, the clinical morphology of the lesions suggested sarcoidosis. Special stains for mycobacteria and fungi were negative., Conclusions: The histologic changes in cutaneous sarcoidosis are more diverse than previously recognized. In sarcoidosis, foreign material may be a frequent nidus for cutaneous granuloma formation. Histologic examination without the clinical history could lead to a misdiagnosis of leprosy, syphilis, other infectious granulomas, rosacea, granuloma annulare, necrobiosis lipoidica, and foreign body reaction in selected cases from this series.

Leiomyomas of the renal pelvis are rare tumors. To date only 4 cases have been reported. We present a unique case with cellular atypia in which ultrastructural and immunohistochemical findings are described.