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Benign lymphangioendothelioma is a rare lesion of controversial etiology and a histopathologic mimic of Kaposi sarcoma and so-called 'well-differentiated' angiosarcoma. Its most typical clinical presentation is as a slowly expanding, erythematous patch or plaque; it rarely presents as a large mass. We report the second case of a giant benign lymphangioendothelioma, which arose as a serpiginous mass involving most of the flank of an elderly male with no prior radiation exposure and with a remote history of herpes zoster infection. A biopsy revealed numerous anastomosing vascular channels extending from the superficial dermis to the subcutis that were dilated to progressively slit-like in architecture. The endothelial cells lacked cytologic atypia, hobnailing, or significant mitotic activity, and human herpesvirus-8 expression was absent. Positivity for podoplanin (D2-40) was observed in the endothelial cells, supporting a lymphatic phenotype. Furthermore, the lesional cells lacked immunohistochemical expression of Wilms tumor 1, providing further support of a malformative - rather than neoplastic - pathogenesis.

Context.-The practice of reporting margin status in biopsies is relatively unique to biopsies of the skin and highly variable among pathologists.Objective.-To address the accuracy of margin evaluation in shave biopsies of nonmelanoma skin cancers.Design.-We collected shave biopsies of squamous and basal cell carcinomas that appeared to have uninvolved margins on routine sign out. We obtained deeper levels on corresponding tissue blocks until blocks were exhausted and examined them for tumor at biopsy margins.Results.-Forty-seven consecutive cases were collected, including 20 squamous cell (43%) and 27 basal cell (57%) carcinomas. Eleven of 47 cases (23%) with negative margins at initial diagnosis demonstrated positive margins upon deeper-level examination. Margins of 8 of 27 basal cell carcinomas (30%) and 3 of 20 squamous cell carcinomas (15%) were erroneously classified as ''negative'' on routine examination.Conclusions.-No guidelines exist regarding the reporting of margins in nonmelanoma skin cancer biopsies, and reporting practices vary extensively among pathologists. We found that nearly one-quarter of positive margins in shave biopsies for cutaneous carcinomas are missed on standard histologic examination. Moreover, reporting of a positive margin may also be misleading if the clinician has definitively treated the skin cancer at the time of biopsy. For these reasons, and as routine exhaustion of all tissue blocks is impractical, the decision to include or exclude a comment regarding the margin status should be given conscious consideration, accounting for the clinical intent of the biopsy and any known information regarding postbiopsy treatment.

In some patients, the presence of monoclonal IgM proteins can cause substantial false elevation in nephelometric assays. A 59-year-old woman with previously unrecognized Waldenström macroglobulinemia had high serum viscosity. Nephelometric analysis revealed elevated measured concentrations of IgG, IgA, and IgM. Pretreatment with a reducing salt solution yielded resolution of cross-linked immunoglobulins into a distinct IgM κ monoclonal protein band by immunofixation electrophoresis. Measured quantitative immunoglobulin measurements in treated and untreated specimens were compared. An approximately 50% drop in IgG and IgA concentrations was observed in the presence of reducing agent, while IgM concentrations were unchanged. We report that the addition of reducing agent solution can alleviate artifactual elevation of nephelometric determination of IgG and IgA concentrations. These results are consistent with dissociation of higher order IgM complexes, leading to reduction of nonspecific light scattering by IgM complexes in IgA and IgG nephelometric reactions.