# Co-occurrence of posterior chest wall pilonidal sinus with melanocytic nevus: a challenging presentation: a case report

## TL;DR

A rare case of a chest wall pilonidal sinus combined with a melanocytic nevus is reported, highlighting diagnostic challenges.

## Contribution

This case report documents an exceptionally rare co-occurrence of posterior chest wall pilonidal sinus and melanocytic nevus.

## Key findings

- The case involved a 46-year-old female with a rare combination of pilonidal sinus and melanocytic nevus on the posterior chest wall.
- Histopathology confirmed the presence of an inflamed pilonidal sinus within a melanocytic nevus.
- The unusual location and combination of these conditions may lead to delayed diagnosis and mismanagement.

## Abstract

To date, only a limited number of case reports have documented the co-occurrence of PNS and melanocytic nevus in the medical literature. This study aims to report an exceptionally rare case of posterior chest wall PNS in conjunction with a melanocytic nevus.

A 46-year-old female presented with a long-standing black lesion on her left upper posterior chest wall, that had become painful in the two months prior to presentation. There was a painful, dark blue, non-erythematous, and non-tender nodule on the left upper posterior chest wall. Based on the patient’s desire for cosmetic purposes, the lesion was excised totally with primary closure under local anaesthesia. Histopathological examination revealed intradermal melanocytic nevus with inflamed pilonidal sinus.

The rarity of posterior chest wall PNS associated with nevi poses unique diagnostic and therapeutic challenges for clinicians. The distinct anatomical location, different from the conventional region, and the rare association between the two conditions may delay accurate diagnosis and result in mismanagement or inappropriate interventions.

The posterior chest wall PNS is another type of atypical PNS that is extremely rare. The association between PNS and blue nevus is a fascinating medical finding that deserves further investigation.