# Dermatomyositis as a Paraneoplastic Syndrome of Metastatic Urothelial Carcinoma

## TL;DR

A man with bladder cancer developed dermatomyositis, which likely signaled cancer recurrence, showing the need for timely cancer reassessment.

## Contribution

This case report highlights dermatomyositis as a potential paraneoplastic indicator of bladder cancer recurrence.

## Key findings

- Dermatomyositis symptoms coincided with metastatic bladder cancer recurrence in a patient with prior cancer history.
- Early dermatomyositis symptoms may be mistaken for medication reactions or unrelated issues in cancer care.
- Multidisciplinary care is crucial for timely evaluation and management of cancer progression in such cases.

## Abstract

Dermatomyositis is an inflammatory condition that causes muscle weakness and distinctive skin rashes, and in some people, it can be a warning sign of an underlying cancer or cancer recurrence. This report describes a man with a prior history of bladder cancer who developed new dermatomyositis symptoms during a period when his cancer initially appeared stable. As his muscle weakness and rash progressed, imaging soon confirmed that the bladder cancer had returned and spread. This close timing supports dermatomyositis as a likely cancer-related (paraneoplastic) condition in this setting and shows how easily early symptoms can be mistaken for medication reactions or other common problems in cancer care. Our case highlights the need for timely reassessment for cancer progression when dermatomyositis develops in patients with current or past bladder cancer, supported by coordinated care between oncology, rheumatology, and dermatology.

A 65-year-old man with history of urothelial carcinoma of the bladder developed dermatomyositis at the time of metastatic disease progression. This temporal association supports a likely paraneoplastic mechanism and highlights the importance of reassessing for disease progression in patients with urothelial carcinoma who develop new-onset dermatomyositis. Early recognition may facilitate timely oncologic evaluation and multidisciplinary management.