# A Linear Affair: Blaschkoid Pattern in Lichen Planus Pigmentosus

## TL;DR

This paper reports a rare case of Lichen Planus Pigmentosus appearing in a linear pattern along Blaschko’s lines, highlighting the importance of recognizing unusual presentations for accurate diagnosis.

## Contribution

The novelty lies in documenting a rare linear/blaschkoid presentation of LPP, which is uncommon and can be misdiagnosed.

## Key findings

- A 32-year-old male presented with linear hyperpigmented lesions along Blaschko’s lines.
- Diagnosis was confirmed using clinical, dermoscopic, and histopathological methods.
- Unusual patterns like this are critical to recognize for accurate differential diagnosis.

## Abstract

Lichen planus pigmentosus (LPP) is an acquired disorder of hyperpigmentation. Atypical presentations, such as linear or blaschkoid distribution, are exceedingly rare and may pose diagnostic challenges. We report a case of a 32-year-old male with pruritic, hyperpigmented, slate-gray to brown macules and patches distributed linearly along Blaschko’s lines on the right upper back and upper limb. The diagnosis of LPP was corroborated by clinical appearance, dermoscopic examination, and histopathological analysis. Recognition of such unusual patterns is essential for accurate diagnosis and to differentiate from other linear pigmentary disorders.