# Red Bumps, Red Flags: A Case Series of Four Neoplasms Masquerading as Inflamed Cutaneous Cysts

## TL;DR

This paper reports four cases where skin bumps initially thought to be cysts were actually tumors, highlighting the need for careful diagnosis.

## Contribution

The study emphasizes the importance of histopathology in distinguishing neoplasms from inflamed cysts.

## Key findings

- Four cases showed erythematous nodules misdiagnosed as cysts but were actually neoplasms.
- Histopathology confirmed diagnoses of dermatofibroma, amelanotic melanoma, dermatofibrosarcoma protuberans, and undifferentiated pleomorphic sarcoma.
- Atypical clinical features like rapid growth or lack of a central punctum suggest neoplasm.

## Abstract

Red, inflamed cutaneous nodules are frequently diagnosed as epidermal inclusion cysts in both primary care and dermatology settings. However, several benign and malignant entities can closely mimic an inflamed cyst, leading to delayed diagnosis and suboptimal management. We present four patients who initially presented with erythematous nodules clinically suspected to be cysts; final histopathologic diagnoses included dermatofibroma, amelanotic melanoma, dermatofibrosarcoma protuberans, and undifferentiated pleomorphic sarcoma. For each case, we describe the clinical presentation, histopathology, and management. The presence of a central punctum and superficial mobility strongly favors an epidermal inclusion cyst. In contrast, the absence of a punctum, rapid growth, deep fixation, a positive dimple sign, or atypical dermoscopic vascular patterns should raise suspicion for a neoplasm. Final diagnosis is based on histopathologic examination, which guides subsequent treatment in accordance with current guidelines. This series underscores the importance of maintaining a broad differential diagnosis for erythematous nodules and obtaining histopathologic confirmation when clinical features are atypical. Early recognition and appropriate biopsy technique may improve patient outcomes.