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BACKGROUND AND DESIGN: A consecutive sample of 46 cases was collected for comparative histologic evaluation. Results of incisional biopsies of cutaneous pigmented lesions interpreted as lentigo maligna, melanoma in situ, or invasive melanoma, and those suggestive, but not diagnostic, of melanoma were collected. Those lesions that were on actinically damaged skin and in which biopsy was followed by complete excision within 6 months were included. Incisional biopsies that removed greater than 50% of the surface area of the lesion were excluded. RESULTS: Of the excisional specimens, 40% demonstrated histopathologic features more pronounced than those in the biopsy specimens. Areas of invasive melanoma not detected in the biopsy specimens were observed in 20% of the excisional specimens. Accurate diagnosis based on small biopsy specimens was not always possible because of the absence of a classic lentigo maligna histologic pattern in many cases. The most frequent deviation from the pattern was the presence of lentiginous epidermal hyperplasia within these lesions. CONCLUSIONS: These results suggest that limited sampling may be inadequate for an accurate diagnosis of pigmented melanocytic lesions on actinically damaged skin. Areas chosen for biopsy may not contain the most advanced areas histologically and may fail to detect foci of invasive melanoma elsewhere within the lesion.

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BACKGROUND: Cutaneous necrosis of the proximal lower extremities in a patient with end-stage renal disease is the classic presentation of calciphylaxis, an untreatable, rare, generally fatal necrotizing cutaneous syndrome. Type 1 primary hyperoxaluria (PH-1) usually presents in childhood with recurrent urolithiasis. Since enzymatic studies to confirm the metabolic defect are now available, some cases of idiopathic renal failure in adulthood have been shown to be caused by PH-1. These patients may develop vascular oxalate deposits resulting in livedo reticularis and distal acral vascular insufficiency. OBSERVATIONS: We describe a patient who presented in end-stage renal failure with proximal lower extremity cutaneous necrosis suggestive of calciphylaxis. A cutaneous biopsy specimen revealed oxalate crystals within blood vessels, and a diagnosis of PH-1 was confirmed enzymatically. CONCLUSIONS: This patient illustrates that PH-1 may present in adulthood, and, in the setting of cutaneous necrosis associated with end-stage renal disease, it may be confused with calciphylaxis. The importance of making a diagnosis of PH-1 is the potential ability to achieve long-term survival by reversing the underlying metabolic defect with hepatic transplantation.

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BACKGROUND AND OBJECTIVE: We identified several patients with a histologic diagnosis of pretibial myxedema in whom thyroid disease was not found. The purpose of this study was to investigate if histologic characteristics can distinguish between pretibial mucinosis secondary to Graves' disease and that unassociated with thyroid disease. METHODS: Biopsy specimens interpreted as compatible with pretibial myxedema were reviewed; these included 12 cases of pretibial mucinosis with documented Graves' disease, and six cases of pretibial mucinosis without evidence of Graves' disease. Ten specimens interpreted as compatible with stasis dermatitis were also evaluated for histologic characteristics, including the possible presence of mucin. RESULTS: Features that distinguish between pretibial mucinosis associated with Graves' disease and pretibial mucinosis without Graves' disease included preservation of a zone of normal-appearing collagen in the superficial papillary dermis (12/12 with Graves' disease, 0/6 without), mucin deposition in the reticular dermis (12/12 with Graves' disease, 0/6 without), lack of mucin deposition in the superficial papillary dermis (11/12 with Graves' disease, 1/6 without), angioplasia (2/12 with Graves' disease, 6/6 without), and the presence of hemosiderin (2/12 with Graves' disease, 6/6 without). Mucin deposition in the papillary dermis was found in six of 10 specimens interpreted as stasis dermatitis. CONCLUSIONS: There are patients with pretibial mucinosis in whom there is no thyroid disease. Specimens from patients without Graves' disease have features of stasis dermatitis in addition to mucinosis. We conclude that pretibial mucinosis may result from stasis or Graves' disease and that histologic differences allow for accurate differentiation.

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