# Osseous Sarcoidosis of the Clivus Causing Cranial Nerve VI Palsy: A Case Report

## TL;DR

A 20-year-old man with a rare case of osseous sarcoidosis in the clivus developed cranial nerve VI palsy, diagnosed through biopsy and treated successfully with immunosuppressive therapy.

## Contribution

This is the first reported case of osseous sarcoidosis of the clivus in a young adult, highlighting its diagnostic and therapeutic implications.

## Key findings

- Osseous sarcoidosis of the clivus is extremely rare, especially in young adults.
- Histopathological analysis confirmed nonnecrotizing granulomas, supporting sarcoidosis diagnosis.
- Treatment with prednisone, adalimumab, and methotrexate resolved symptoms after six months.

## Abstract

Sarcoidosis is an inflammatory condition characterized by the presence of noncaseating, or nonnecrotizing, granulomas in one or more organ systems. It has a wide range of clinical presentations and often mimics other conditions, making it difficult to diagnose. Osseous sarcoidosis of the skull base is extremely rare and has not previously been reported in a young adult patient. A 20-year-old man with a prior diagnosis of chronic recurrent multifocal osteomyelitis and pulmonary nodules of unknown etiology presented with six weeks of intractable headache and eye pain, followed by acute-onset complete right-sided sixth cranial nerve palsy. Imaging revealed a lesion of his clivus, extending into the cavernous sinus, along with inflammation of his paranasal sinuses. Extensive workup was negative for infection. Histopathological analysis of a biopsy of the lesion showed chronic inflammation with nonnecrotizing granulomas without evidence of infection or vasculitis, supporting a diagnosis of sarcoidosis. He was treated with prednisone, adalimumab, and adjunctive methotrexate, and had resolution of his symptoms after six months. Osseous involvement in sarcoidosis is uncommon, particularly in the pediatric and young adult populations. Although rare, sarcoidosis should be included in the differential diagnosis for patients with sterile, inflammatory bone lesions. Careful evaluation for additional clinical features of sarcoidosis and thorough histopathological evaluation of the bone biopsy for evidence of granulomatous inflammation, as well as exclusion of alternative etiologies of granulomatous disease, help distinguish these conditions.