# Unusual presentation of histiocytosis X in the cranial vault: A rare case report

## TL;DR

A rare case of histiocytosis X in an infant's skull is reported, highlighting the unusual presentation and diagnostic process.

## Contribution

This case report adds to the limited understanding of histiocytosis X's presentation in the cranial vault in infants.

## Key findings

- An 11-month-old infant presented with a parieto-occipital swelling diagnosed as histiocytosis X.
- The case showed no recurrence or additional localizations after surgical removal and follow-up.
- Cranial vault involvement is a known but rare manifestation of histiocytosis X in children.

## Abstract

Langerhans histiocytosis or histiocytosis X is an oligo-clonal proliferation of Langerhans cells. We report the case of an 11-month-old infant who had presented with a parieto-occipital swelling since birth, which progressively increased in volume without any other presenting signs. The radiological work-up initially suspected osteitis of the vault, which was removed in its entirety. The anatomopathological study concluded that it was histiocytosis X. The extension work-up was negative. Follow-up of this patient showed no local recurrence or appearance of other localizations.

A review of the literature shows that little is known about its pathophysiology. It mainly affects children and young adults. There are several possible sites of involvement, and cranial vault involvement is a fairly frequent form among the bony sites of this pathology. The diagnosis is confirmed histologically or cytologically, and extension workup is required to confirm the diagnosis. Therapeutic management has not been standardized, and sometimes requires chemotherapy in addition to surgery. The prognosis depends on whether vital organs are affected or not.