PD-L1 Expression in Anal Intraepithelial Neoplasia Versus. Invasive Squamous Cell Carcinoma

Introduction/Objective Upregulation of programmed death-ligand 1 (PD-L1), an immunoregulatory protein is associated with adverse outcome in several malignancies. Very few studies have evaluated PD-L1 expression in anal lesions. In this study we compare PD-L1 expression in anal squamous intraepithelial lesions (SIL/AIN) with that in invasive squamous cell carcinoma (ISCC) Methods After IRB approval, formalin-fixed paraffin embedded sections from 84 patients (51 with ISCC and 32 without ISCC), from 2010–2018, were immunostained for PD-L1 (Dako 22C3 monoclonal antibody). These included 15 cases with normal mucosa, 60 cases with low grade squamous intraepithelial lesion (LSIL/AIN 1), 52 cases with high grade intraepithelial lesion (HSIL/AIN2-3), and 51 cases of ISCC. Overall tumor proportion score of > 1% tumor cells with partial or complete membrane staining was interpreted as PD-L1 positive (PD-L1 +). Results PD-L1 was positive in 18/51 (35%) and negative in 33/51 (65%) cases of ISCC. Staining was heterogenous in all PD-L1 positive cases, with invasive foci that were negative to 100% positive. Tumor proportion score ranged from 1% to 50%. No PD-L1 membrane positivity was seen in any of the normal mucosa, LSIL/AIN 1, and HSIL/AIN 2-3. Even in cases of microinvasive or invasive carcinoma, PD-L1 positivity was seen only in the invading malignant cells and not in the overlying or adjacent HSIL. One case showed aberrant nuclear staining in 10% of cells in LSIL and HSIL. About 25% of cases showed non-specific basal granular cytoplasmic staining in normal mucosa, LSIL, and HSIL, that correlated with the presence of melanin. Cases with normal mucosa, LSIL/AIN 1, and HSIL/AIN 2-3, were equally distributed between cases with no invasive carcinoma, PD-L1 positive ISCC, and PD-L1 negative ISCC. Conclusion No PD-L1 positivity (membrane staining) was present in normal mucosa or anal squamous intraepithelial lesion/anal intraepithelial neoplasia in our study. Any nuclear staining or granular cytoplasmic staining should not be interpreted as PD-L1 positivity. PD-L1 was only positive in a subset (35%) of invasive squamous cell carcinoma. The expression of PD-L1 is likely to be associated with an invasive malignant process and is a potential target for therapy with PD-L1 inhibitors.

Immunohistochemical analysis of kallikrein-related peptidases in the normal kidney and renal tumors: potential clinical implications

Kallikrein-related peptidases (KLKs) have been shown to be differentially expressed in various malignancies and shown to be useful tumor markers. Previous immunohistochemistry (IHC) analysis demonstrated that KLKs 5, 6, 10, and 11 have a potential prognostic significance in renal cell carcinoma (RCC). To further explore the significance of KLKs, we examined KLKs 1, 6, 7, and 15 in different subtypes of renal tumors. KLK1 has stronger expression in high grade compared to low grade clear cell RCC. However, KLK6 and KLK7 show strong expression in low grade in contrast to high grade clear cell RCC. Furthermore, the expression of KLK7 can distinguish between oncocytoma and chromophobe RCC. Oncocytoma showed diffuse, strong granular cytoplasmic staining, but chromophobe RCC showed focal weak homogeneous cytoplasmic stain. The pattern of staining of different KLKs can also be helpful in differentiating some of the subtypes of renal tumors. Our results show the potential ability of KLKs to serve as diagnostic markers and expand previous data about the prognostic significance of KLKs in kidney cancer. In addition, our study is the first to show the ability of KLK staining to distinguish various types of kidney cancers when morphology is similar.

Testicular Interstitial Cell Tumor and Gynecomastia in a Rabbit

Unilateral testicular interstitial (Leydig) cell tumor and gynecomastia were diagnosed in an adult male rabbit. The interstitial cell tumor was a well-circumscribed, 2-mm diameter, pale tan nodule composed of a uniform population of polygonal cells. Neoplastic interstitial cells exhibited diffuse, granular cytoplasmic staining with Melan A, a marker of steroid-producing cells in humans and dogs. Multiple subcutaneous masses in the caudal abdomen were associated with enlarged nipples and consisted of hyperplastic mammary gland tissue with proliferation of ducts and alveoli, marked lobule formation, and pseudolactational hyperplasia. Many epithelial cells lining the hyperplastic ducts and alveoli exhibited intense nuclear expression of progesterone receptor antigen, whereas myoepithelial cells showed strong nuclear staining for p63 antigen. This is the first report of concurrent interstitial cell tumor and gynecomastia in a rabbit and also the first description of gynecomastia in this species.

Oncocytic Biliary Cystadenocarcinoma: A Case Report and Review of the Literature

We report an unusual case of biliary cystadenocarcinoma with oncocytic differentiation. The patient was a 43-year-old woman who presented with right upper quadrant pain. Imaging revealed a 16 × 10 × 10-cm, heterogenous, right hepatic mass with extension into the right atrium. Surgical resection revealed a papillary neoplasm of malignant cells with atypical hyperchromatic nuclei and prominent nucleoli lining fibrovascular cores. Mesenchymal stroma was not present. The majority of the epithelial cells had abundant eosinophilic granular cytoplasm, consistent with oncocytic differentiation. There was extensive stromal and hepatic parenchymal invasion. Immunohistochemical staining revealed a “biliary pattern” of cytokeratin subset immunoreactivity, with positivity for cytokeratin 7 and an absence of staining with cytokeratin 20. The tumor was negative for mucin, carcinoembryonic antigen, α-fetoprotein, calretinin, CD31, and chromogranin. There was granular cytoplasmic staining with phosphotungstic acid hematoxylin, consistent with the presence of abundant mitochondria. Electron microscopy revealed abundant mitochondria within the neoplastic cells. This case is quite unusual because female patients only rarely lack the characteristic ovarian-like mesenchymal stroma of biliary cystadenomas/cystadenocarcinomas. Furthermore, to our knowledge, oncocytic differentiation in this neoplasm has been reported previously on only 2 occasions. The biologic behavior and prognostic significance, if any, of the lack of mesenchymal stroma in female patients or the presence of oncocytic differentiation remains to be further elucidated as more of these cases are described.