# Novel Ultrastructural Insights into the Clear-Cell Carcinoma of the Pancreas: A Case Report

## TL;DR

This case report provides new ultrastructural insights into a rare and aggressive form of pancreatic cancer called clear-cell carcinoma.

## Contribution

The study reveals that disrupted mitochondria are linked to the clear-cell nature of this cancer subtype.

## Key findings

- The tumor cells showed a clear-cell appearance with abundant intracytoplasmic vacuoles.
- Transmission electron microscopy revealed a massive presence of structurally disrupted mitochondria.
- Negative staining for NDUFA4L2 suggests a specific molecular characteristic of the tumor.

## Abstract

Pancreatic cancer, most frequently as ductal adenocarcinoma (PDAC), is the third leading cause of cancer death. Clear-cell primary adenocarcinoma of the pancreas (CCCP) is a rare, aggressive, still poorly characterized subtype of PDAC. We report here a case of a 65-year-old male presenting with pancreatic neoplasia. A histochemical examination of the tumor showed large cells with clear and abundant intracytoplasmic vacuoles. The clear-cell foamy appearance was not related to the hyperproduction of mucins. Ultrastructural characterization with transmission electron microscopy revealed the massive presence of mitochondria in the clear-cell cytoplasm. The mitochondria showed disordered cristae and various degrees of loss of structural integrity. Immunohistochemistry staining for NADH dehydrogenase [ubiquinone] 1 alpha subcomplex, 4-like 2 (NDUFA4L2) proved specifically negative for the clear-cell tumor. Our ultrastructural and molecular data indicate that the clear-cell nature in CCCP is linked to the accumulation of disrupted mitochondria. We propose that this may impact on the origin and progression of this PDAC subtype.