Salivary gland-type tumors have been rarely described in the thyroid gland. Mammary Analog Secretory Carcinoma (MASC) is a recently defined type of salivary gland carcinoma characterized by a t(12;15)(p13;q25) resulting in an ETV6-NTRK3 fusion gene. We report 3 cases of MASC involving the thyroid gland without clinical evidence of a salivary gland or breast primary; the clinico-pathologic characteristics are reviewed. Assessment for rearrangement of the ETV6 (12p13) locus was conducted by fluorescence in situ hybridization (FISH) on representative FFPE sections using an ETV6 break apart probe (Abbott Molecular, Des Plaines, IL, USA). The patients were two females (52 and 55 years-old) and 1 male (74 years-old). The tumors were poorly circumscribed solid white tan nodules involving the thyroid. Histologically, they were invasive and showed solid, microcystic, cribriform, and tubular growth patterns composed of variably bland polygonal eosinophilic cells with vesicular nuclear chromatin and conspicuous nucleoli. All three cases showed metastasis to lymph nodes; one case showed lateral neck involvement. The tumor cells were positive for S100 and mammaglobin. GATA-3 and PAX-8 were positive in 2 cases, one of which only focally so. All three cases were negative for TTF-1 and thyroglobulin. Rearrangement of the ETV6 locus was confirmed in all cases and a diagnosis of MASC rendered for each case. A site of origin distinct from the thyroid gland was not identified, with a median follow up of 24 months. MASC may rarely involve the thyroid gland. The origin of these lesions is unknown; while an origin from ectopic salivary gland-type cells is entertained, a metastatic origin from an occult primary cannot be definitively excluded at this time. Given the histologic (follicular-like microcystic pattern with colloid-like secretions and papillary pattern), immunophenotypic (PAX-8), and even molecular overlap, MASC can be mistaken for papillary thyroid carcinoma and should be considered in the differential diagnosis of a thyroid mass.

Fixed drug eruption (FDE) is a cutaneous reaction to a medication that recurs in the same fairly localized site with each exposure to the offending drug. The classical histopathologic findings in FDE consist of an interface dermatitis with predominantly lymphocytic inflammatory cell infiltrate. An unusual case of FDE in a 27-year-old pregnant woman who presented with widespread lesions and a predominantly neutrophilic infiltrate on histopathologic examination is reported.

There is limited information on the direct role of the neutralizing antibody responses against hepatitis C virus (HCV) infection or methodologies to study them. Previously we have demonstrated that interleukin-10 (IL-10) administered to chronic hepatitis patients led to a decrease in disease activity, but an increase in HCV viral burden. The mechanism behind this is unknown. The objective of this study was to examine the antibody response in IL-10-treated patients. To establish a neutralization antibody assay, HCV-positive and HCV-negative sera were collected and incubated with HCV strain JFH-1 particles before culture with Huh 7.5 cells. Viral replication was measured a week later by either indirect immunofluorescence assay (iIFA) or real-time reverse transcriptase polymerase chain reaction (RT-PCR). After validation of the methodology, the sera from 30 previously-described subjects of a group previously treated with IL-10 were tested for the neutralization capacity of their antibodies. The amount of total anti-HCV antibody in the sera was also measured by direct staining of HCV full-length replicon cells. With this validated neutralization assay for anti-HCV antibodies we found that HCVneutralizing antibodies are universally present, but with significantly different titers. In patients who were treated with IL-10, the total anti-HCV antibody titers appear to be constant, but with significantly decreased antibody neutralization activity. Our study validates an assay to quantitatively determine the presence and strength of HCV-specific neutralizing antibodies. We have found that IL-10-treated patients have significantly lower HCV antibodies, but maintain the total anti-HCV antibody titer, suggesting a novel mechanism by which IL-10 treatment increases viral load in patients.

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