Background:programmed death-ligand 1 (PD-L1) is a ligand for the inhibitory programmed cell death protein 1 (PD-L1), which are targeted by several anti-PD-1 and PD-L1 drugs for lung cancer treatment. In clinical practice, many lung cancer cases only have cytology samples available to test PD-L1. Our current study compared the PD-L1 immunohistochemistry (IHC) between paired cytological and surgical samples.Materials and Methods:Formalin-fixed lung cancer tissue microarray and paired cell blocks and surgical specimens from the same patients with a confirmed diagnosis of lung squamous cell carcinoma (SCC, n = 29) and adenocarcinoma (AC, n = 23) were sectioned for PD-L1 IHC.Results:PD-L1 was expressed on tumor cells in 16 of 29 (55%) SCC surgical specimens and 18 of 29 (62%) paired cytologic specimens with 83% matched immunostains. PD-L1 was expressed on tumor cells in 13 of 23 (57%) AC surgical specimens and in 17 of 23 (74%) paired cytologic specimens with 79% matched immunostains. The PD-L1 was expressed on inflammatory cells in 20 of 23 (87%) AC surgical specimens and in 15 of 23 (65%) paired cytologic specimens with 70% matched immunostains. The PD-L1 was expressed on inflammatory cells in 18 of 29 (62%) SCC surgical specimens and in 12 of 29 (41%) paired cytologic specimens with 79% matched immunostains.Conclusions:PD-L1 immunostain in cytology samples matched very well with paired surgical samples in both SCC and AC cases. The cytologic samples present slightly higher sensitivity for PD-L1 immunostain on tumor cells as compared to surgical biopsies.

Mixed adenoneuroendocrine carcinomas, spindle cell carcinomas, and clear cell carcinomas are all rare tumors in the biliary tract. We present the first case, to our knowledge, of an extrahepatic bile duct carcinoma composed of all three types. A 65-year-old man with prior cholecystectomy presented with painless jaundice, vomiting, and weight loss. CA19-9 and alpha-fetoprotein (AFP) were elevated. Cholangioscopy revealed a friable mass extending from the middle of the common bile duct to the common hepatic duct. A bile duct excision was performed. Gross examination revealed a 3.6 cm intraluminal polypoid tumor. Microscopically, the tumor had foci of conventional adenocarcinoma (CK7-positive and CA19-9-postive) surrounded by malignant-appearing spindle cells that were positive for cytokeratins and vimentin. Additionally, there were separate areas of large cell neuroendocrine carcinoma (LCNEC). Foci of clear cell carcinoma merged into both the LCNEC and the adenocarcinoma. Tumor invaded through the bile duct wall with extensive perineural and vascular invasion. Circumferential margins were positive. The patient's poor performance status precluded adjuvant therapy and he died with recurrent and metastatic disease 5 months after surgery. This is consistent with the reported poor survival rates of biliary mixed adenoneuroendocrine carcinomas.

Solitary fibrous tumor is a rare, benign spindle cell neoplasm that was first described in the thoracic pleura. This tumor is now known to occur at many extrapleural sites. There are established criteria for the diagnosis of malignant solitary fibrous tumor including ≥4 mitotic figures per 10 high-power fields, increased cellularity, cytologic atypia, infiltrative margins, and/or necrosis. Although all solitary fibrous tumors have the potential to recur or metastasize, those with malignant histologic features tend to behave more aggressively. We report a case of solitary fibrous tumor, with malignant histologic features, in a 21-year-old woman which arose from the serosal surface of the sigmoid colon.

Primary esophageal malignant melanoma (MM) is rare and extremely aggressive. For pathologists, it can be challenging to diagnose and differentiate from other poorly differentiated malignant neoplasms in the esophagus. Complicating this fact, MM can have divergent differentiation and express nonmelanocytic immunohistochemical markers including epithelial markers (cytokeratins) and rarely neuroendocrine markers. Lack of awareness of this fact by a pathologist can lead to an erroneous diagnosis and delay treatment for an already aggressive disease. Herein, we report a case of primary esophageal malignant melanoma with aberrant CD56 expression without accompanying synaptophysin or chromogranin expression.

GATA3 is a transcription factor involved in the development and differentiation of lymphocytes, breast, and hair follicles. The protein is a useful immunohistochemical (IHC) marker for supporting diagnoses of breast or urothelial carcinoma. This can be especially helpful in metastatic neoplasms to help delineate site of origin. GATA3 is also reportedly positive in a percentage of pancreatic ductal adenocarcinomas (PDACs) and cholangiocarcinomas (CCs), but no study has closely evaluated this relationship with respect to clininopathologic features or patient outcome. Using tissue microarrays, we analyzed 240 PDACs and 60 CCs with GATA3 IHC and compared expression to various clinical and pathologic parameters. Overall, GATA3 positivity was seen in 16% of PDACs and 5% of CCs. GATA3 positivity in PDAC cases was more common in male patients (P=0.013). GATA3-positive PDACs trended toward worse survival on multivariate analysis (P=0.074). The only 3 GATA3-positive CCs were poorly differentiated (P=0.069); low case number precluded multivariate survival analysis for CCs. GATA3 positivity can occur in carcinomas of the pancreatobiliary system, which should be considered during IHC workup of neoplasms of unclear origin. This positivity seems to have minimal relevance to patient outcome.