Background Reliable nuclear immunohistochemical stains for sebaceous neoplasms have not been readily available. Positive nuclear staining has been reported for GATA3 and factor XIIIa (AC‐1A1). We sought to determine the diagnostic utility of these nuclear stains by comparing their staining pattern to adipophilin, a consistently positive cytoplasmic stain. Methods Cases with the diagnosis of sebaceous hyperplasia, sebaceous adenoma, sebaceous epithelioma/sebaceoma, sebaceous carcinoma, and nonsebaceous neoplasms (basal cell carcinoma and squamous cell carcinoma) were examined. Intensity and extent of staining of the basal cells and mature sebocytes were evaluated for each stain. Results Factor XIIIa (AC‐1A1) was 87.3% sensitive and 95.1% specific for all sebaceous neoplasms sand showed high inter‐observer reliability. Adipophilin was 83.2% sensitive and 87.8% specific. GATA3 was the least sensitive (80.9%) and specific (75.6%) marker. When factor XIIIa was compared against composite staining of all three markers its staining was still uniquely significant (P = .0210). Conclusion Factor XIIIa (AC‐1A1) is a sensitive and specific nuclear marker for sebaceous differentiation. Its diagnostic utility exceeds that of adipophilin. Factor XIIIa should be included in the expanding group of immunohistochemical and special stains which can be utilized to aid in the diagnosis of sebaceous neoplasms.

Background Epstein-Barr virus- (EBV-) associated lymphoproliferative disease (LPD) is a rare condition, usually occurring in immunocompromised patients. We report a case of EBV-associated LPD in a patient with severe celiac disease, the first report to describe this syndrome in a patient with this diagnosis. Case Summary A 69-year-old Caucasian woman with recent diagnosis of celiac sprue presented to our hospital with persistent diarrhea, abdominal pain, weight loss, and fatigue despite adherence to gluten-free diet for a number of weeks prior to presentation. She underwent evaluation for occult malignancy and was found to have diffuse intra-abdominal mesenteric lymphadenopathy on CT scan. Biopsy of mesenteric nodes revealed an EBV positive, CD20 positive mixed lymphoproliferative process with T-cell predominance, but without a monoclonal cell population felt to be consistent with EBV-associated LPD. Bone marrow biopsy revealed hemophagocytic lymphohistiocytosis, complicating her course. She was treated with steroids and rituximab but continued to decline, eventually developing MSSA bacteremia and succumbing to her disease. Conclusion To our knowledge, this is the first report of the constellation of celiac sprue, EBV-associated LPD, and hemophagocytic lymphohistiocytosis. Providers caring for patients with severe, uncontrolled celiac disease and adenopathy should consider EBV-associated LPD.

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