Langerhans cell histiocytosis (LCH) is a rare disease of the dendritic cell system and often involves the orbit. In fact, the impact on the orbit can sometimes be the first and only symptom. LCH can affect anyone, but especially patients between the ages of five and 10. Unfortunately, diagnosis is a challenge because LCH can imitate other conditions, such as periorbital hematoma, rhabdomyosarcoma, neuroblastoma malignant lacrimal gland tumor, orbital cysticercosis or orbital tuberculosis. Now, research is showing that MRI can effectively diagnose LCH patients.

Researchers in China evaluated 23 patients with a mean age of 6.3 years and histopathology-confirmed LCH of the orbit. They reviewed clinical manifestations and MRI for symptoms, disease duration, location, configuration, margin, MRI signal intensity and enhanced performance.

The patients’ symptoms included swollen eyelids, exophthalmos and a palpable mass. Fourteen patients presented with swollen eyelids or exophthalmos. All but one involved unilateral orbits. One patient had a cough and expectoration, and another had polydipsia and polyuria. Lesions were located in the superior or superlateral orbital roof of 74% of patients.

Some lesions formed masses or irregular shapes. Twelve cases appeared heterogeneous isointense, 43.5% showed iso-hypointense on T1-weighted imaging, and 65.2% showed hyper-hypointense mixed signals on T2-weighted imaging. The researchers noted Seven cases had patchy hyperintense signal on T1-weighted imaging, and 11 showed markedly hyperintense signal near the edge of lesions on T2-weighted imaging. After enhancement, 91.3% of lesions presented marked enhancement at the edges and the surrounding tissues with heterogeneous obvious enhancement of the lesion center. The lesions in four patients were surrounded by a low circular signal.

Wu C, Li K, Hei Y, et al. MR imaging features of orbital Langerhans cell histiocytosis. BMC Ophthalmol. December 19, 2019. [Epub ahead of print].