# A diagnostic dilemma—to operate or not to operate—a rare case report

## TL;DR

A 41-year-old man with a complex flank swelling faces a difficult decision between surgery or nonsurgical treatment due to an uncertain diagnosis.

## Contribution

This case report highlights diagnostic challenges in distinguishing sarcoma from lymphomatous malignancy and plasmacytic infiltrate.

## Key findings

- Initial core biopsy suggested undifferentiated sarcoma, but further testing indicated lymphomatous origin.
- Final diagnosis was plasmacytic infiltrate of uncertain clinical significance.
- No definitive treatment plan could be decided due to diagnostic uncertainty.

## Abstract

A 41-year-old male presented with a swelling in the right flank present since 2 years. Initially, it was small in size but increased in size for the past 6 months. Examination revealed a large swelling in the right flank that was soft in consistency and attached to the deeper muscle. CT scan revealed a heterogenous complex swelling with attachment to the underlying muscle. Core biopsy of the lesion was reported as undifferentiated sarcoma. After immunohistochemistry markers, the diagnosis was revised to a malignancy of a lymphomatous origin. Gene sequencing studies and extensive higher marker studies were done and a final diagnosis of plasmacytic infiltrate of uncertain clinical significance was reported. With no further diagnostic options available, the case still remains to be a diagnostic challenge as the choice of treatment between surgical resection and nonsurgical treatment with chemotherapy and/or radiation cannot be decided upon.