Granulomatous Pneumocystis jiroveci Pneumonia in an HIV-Positive Patient on Antiretroviral Therapy: A Diagnostic Challenge.

Human Immunodeficiency Virus (HIV)-related Opportunistic Infections (OI), including Pneumocystis jiroveci pneumonia (PCP), have become much less commonplace with anti-retroviral therapy (ART). Despite this, OIs are still common and it is important to remain vigilant for their presence and be aware of how ART and OI chemoprophylaxis may lead to atypical disease presentations. We present the case of a 51-year-old woman with HIV and CD4+ T helper lymphocytes cell count > 200 cells/ul on both ART and trimethoprim/sulfamethoxazole prophylaxis who presented with cavitating lung masses, mediastinal lymphadenopathy and pleural effusions. Negative bronchoalveolar lavage (BAL) and transbronchial biopsy (TBBx) prompted a second diagnostic procedure with a transthoracic core needle biopsy; the final diagnosis was granulomatous PCP. This case showcases a very rare presentation of PCP, with both large cavitating lung masses on imaging and granulomatous reaction on pathology, as well as the challenge of a potentially missed diagnosis with negative BAL and TBBx requiring transthoracic core needle biopsy for a final diagnosis.

Nested Variant of Urothelial Carcinoma Is a Luminal Bladder Tumor With Distinct Coexpression of the Basal Marker Cytokeratin 5/6.

OBJECTIVES: The nested variant of urothelial carcinoma (NVUC) is a rare bladder tumor that may possess a luminal molecular phenotype. We sought to determine whether a small immunohistochemical (IHC) panel using common surrogates for molecular phenotypes would reliably classify a cohort of pure NVUC cases. METHODS: IHC staining with a panel composed of markers for basal subtypes (CK5/6, CK14) and luminal subtypes (FOXA1, GATA3) was performed on pure small NVUC cases (n = 23) and 5 large NVUC cases (n = 5). Scoring of IHC stains was performed semiquantitatively. Individual cases were analyzed using previously reported IHC-based surrogates for molecular subtype. RESULTS: The phenotype of NVUC was classified as luminal from 60.1% (FOXA1+/CK5/6-) to 100% (GATA3+/CK14-) of cases using composite phenotypes. No cases possessed a basal or squamous cell carcinoma-like phenotype. The majority of small NVUC cases (69.5%) showed subset CK5/6 expression distinctly localized to the basal layers of tumor cell nests. Intratumoral heterogeneity was also noted in CK5/6 (21.7% of small NVUC cases) but no other markers. CONCLUSIONS: NVUC appears to express markers of both basal and luminal bladder tumors. Definitive gene expression profiling may be valuable to further characterize this unique histologic variant.