Ki-67 expression in pulmonary tumors-reply

The pathological characteristics of enzootic nasal adenocarcinoma in goats

Introduction

Enzootic nasal adenocarcinoma (ENA) is a nasal cancer that occurs in goats and sheep infected by enzootic nasal tumour virus. Pathologic examinations are useful for distinguishing tumours from inflammatory hyperplasia. The aim of this study was to describe the pathological characteristics of ENA.

Material and Methods

Caprine tumour samples were collected for pathological examination. The tissue sections were stained with haematoxylin-eosin and periodic acid-Schiff (PAS) and processed for immunohistochemical staining. Tumour samples were also processed for routine transmission electron microscopy (TEM).

Results

The histopathological structure of the tumours exhibited both papillary formations in the superficial regions and tubular or acinar formations in the deeper layers, representing distinct structural patterns within the same adenocarcinoma. The tumour cells were positive for PAS, and mitotic figures were rare. Low-differentiated cancer nests and epithelial-mesenchymal transition phenomena were observed. Immunohistochemical analysis showed that the tumour cells were strongly positive for pancytokeratin and cytokeratin (CK)18, moderately positive for CK7, and did not express olfactory marker protein. The Kiel 67 labelling index was approximately 23%. Retrovirus-like particles were distributed inside and outside of acinar tumour cells in TEM.

Conclusion

The origin site of ENA is the epithelium of the nasal glandular tubules. This cancer is a low-grade adenocarcinoma with malignant potential. Cytokeratin 7 and CK18 can be considered immunophenotypes for identifying ENA tumour cells.

[Immunophenotyping of lung tumors : An update]

The WHO Classification of Lung Tumors (2015) established the use of immunohistochemical stainings for resection specimens, however, detailed recommendations had been missing. Now, an international expert panel has summarized key questions for daily routine practice and provided recommendations to assist the community in the appropriate use of immunohistochemistry in this context. This article provides an overview of the most important aspects.

Analysis of the proliferative activity in lung adenocarcinomas with specific driver mutations

In the last decade it became evident that many lung adenocarcinomas (ADC) harbor key genetic alterations such as KRAS, EGFR or BRAF mutations as well as rearrangements of ROS1 or ALK that drive these tumors. In the present study we investigated whether different driver mutations of ADC result in different proliferation rates, which might have clinical impact, including resistance to therapy, recurrence and prognosis. We analyzed the proliferation index (PI) on full slides of surgically resected ADC (n = 230) with known genetic aberrations by means of immunohistochemistry and subsequent digital image analysis and correlated the results with clinicopathological variables including overall (OS) and disease free survival (DFS). We did not observe significant differences in OS or DFS regarding the KRAS or EGFR mutational status (P = 0.56). However, KRAS mutated ADC showed an increased PI compared to EGFR mutated ADC, and ADC with ALK translocations (P < 0.01). Subgroup analysis of EGFR mutated ADC showed a higher PI for tumors harboring a mutation in exon 18 and 20, compared to tumors with a mutation in exon 19 or 21. A PI of 11.5% was the best possible prognostic stratificator for OS (P = 0.01 in KRAS mutated and P < 0.01 in EGFR mutated ADC). In conclusion, the PI differs significantly among ADC with distinct driver mutations. This might explain the varying indications for a prognostic relevance of the PI observed in prior studies. Our study provides a basis for the establishment of a reliable and clinically meaningful PI threshold.