CD163 Immunohistochemical "Circle Sign" Staining Pattern Differentiates Sinonasal Papillomas From Morphologically Similar Non-neoplastic Lesions.

Sinonasal papillomas are a diverse group of benign epithelial neoplasms of the sinonasal tract. Inverted papilloma, in particular, must be distinguished from other lesions with no malignant potential. The aim of this study was to distinguish sinonasal papillomas from morphologically similar lesions using CD163 immunostaining. Cases from a 19-year period were identified. These included 49 inverted, 10 exophytic, and 12 oncocytic papillomas, 21 chronic sinusitides with squamous metaplasia, 27 inflammatory polyps, 5 verrucae vulgares, 5 respiratory epithelial adenomatoid hamartomas, and 6 DEK::AFF2 carcinomas of the sinonasal tract. A subset of biopsy cases (8 inverted papillomas, 5 inflammatory polyps) was separately analyzed. CD163 immunohistochemistry (IHC) was performed. A unique "circle" staining pattern was identified in the surface epithelium. After locating a hotspot, circles were quantified in 10 consecutive high-power fields. Circles were present in 66/71 (93%) cases of sinonasal papilloma, with a mean of 35 circles/10 HPF (range: 0 to 160/10 HPF) and a median of 19 circles/10 HPF. Circles were present in 20/58 (34%) non-neoplastic cases, with a mean of 2 circles/10 HPF (range: 0 to 27/10 HPF) and a median of 0. Considering all resection and biopsy cases, performance for distinguishing papillomas from non-neoplastic lesions was best at a cutoff of 10 circles/10 HPF (2-tailed P <0.0001) with sensitivity, specificity, positive predictive value, and negative predictive value of 66.2%, 93.1%, 92.1%, and 69.2%, respectively. The results were similar in the biopsy subset. One other neoplastic entity, the DEK::AFF2 carcinomas, also showed prominent CD163 circle staining. In summary, sinonasal papillomas demonstrate extensive CD163 "circle" staining in the epithelium compared with the non-neoplastic lesions studied. As such, the "circle sign" on CD163 IHC may be helpful in distinguishing between diagnoses, particularly on small biopsies or equivocal specimens.

Successful Orthotopic Heart Transplantation in a Patient with Anti-U Antibody.

OBJECTIVE: The U (universal) antigen is part of the MNS blood group present at a frequency of nearly 100% in Caucasians and 98% of African Americans. The anti-U antibody is clinically significant and has been reported to cause hemolytic transfusion reactions and hemolytic disease of the fetus and newborn. METHODS: Routine forward and backward typing, direct antiglobulin testing, and an antibody screen were performed. In addition, red blood cell phenotype and adsorption studies were also performed. RESULTS: The patient was found to have a rare anti-U antibody, rendering all available inventory in our hospital incompatible for transfusion. CONCLUSION: This is the first reported case of solid organ transplantation in a patient with an anti-U alloantibody. Appropriate pretransplant evaluation and coordination between the clinical team and transfusion medicine service must be optimized to procure rare packed red blood cell units in a timely manner.

Rapidly fatal pneumonitis from immunotherapy and concurrent SARS-CoV-2 infection in a patient with newly diagnosed lung cancer.

Immune checkpoint inhibitors (ICIs) are used for the treatment of numerous cancers, but risks associated with ICI-therapy during the COVID-19 pandemic are poorly understood. We report a case of acute lung injury in a lung cancer patient initially treated for ICI-pneumonitis and later found to have concurrent SARS-CoV-2 infection. Post-mortem analyses revealed diffuse alveolar damage in both the acute and organizing phases, with a predominantly CD68+ inflammatory infiltrate. Serum was positive for anti-SARS-CoV-2 IgG, suggesting that viral infection predated administration of ICI-therapy and may have contributed to a more fulminant clinical presentation. These data suggest the need for routine SARS-CoV-2 testing in cancer patients, where clinical and radiographic evaluations may be non-specific.