Early adult-onset orbital apex Langerhans cell histiocytosis histologically confirmed during “truly spontaneous” regression

Abstract

Dear Editor, There are few reports addressing the appearance of Langerhans cell histiocytosis (LCH) in the sphenoid sinus and superior orbital fissure region [8], despite many reports of fronto-orbital LCH. We present an early adult case of left orbital apex LCH that was histologically confirmed during spontaneous regression. In the present case, regression was observed before any therapeutic intervention so that the regression in this case can be described for certain as “truly spontaneous” regression, not subsequent to any intervention. A 22-year-old man had an acute intermittent throbbing pain in the left temporal region that lasted for 2 days. After the pain subsided, he developed blurred vision of the left eye. The blurred vision of the left eye improved the following week. Magnetic resonance imaging (MRI) showed an enhanced left orbital apex lesion involving the sphenoid sinus (Fig. 1a). Despite gradual regression on follow-up MRI (Fig. 1f–j), optical coherence tomography revealed irreversible retinal damage of the left eye (Fig. 1b). For histological diagnosis to set the therapeutic strategy for the regressing orbital lesion, endoscopic endonasal biopsy confirmed the orbital lesion in the course of regression was LCH (Fig. 1d, e). Systemic work-up showed no further LCH lesions in other regions. This single-system, singlesite LCH has been kept under careful observation and follow-up. The orbital LCH shrank back to almost normal structure over 7 months after the regression occurred. While five reports of regressed orbital LCH are available [2–4, 6, 7], in each case, regression occurred after therapeutic interventions such as surgery or biopsy. Among them, our case is the first of adult LCH with spontaneous regression. We also have a paediatric case of regressed isolated neurohypophyseal LCH with diabetes insipidus [5], in which regression occurred after biopsy. Although “spontaneous regression” is often used in case reports of various fields, “truly spontaneous” regression is, in reality, extremely rare [9]. Differential diagnosis of lesions involving the orbital wall includes dermoid cysts, lymphangioma, mucocele, meningioma, tumours of the lachrymal gland, primary bone and soft tissue tumours, and metastases [10]. Adult onset LCH, though rare, should be included in the differential diagnosis of lytic lesions of the lateral orbital wall in an adult patient. Histopathological confirmation is crucial in fluctuating orbital lesions like in this case, because exclusion diagnosis from malignancies or from potentially recurrent lesions should be given. Spontaneous regression of cancer is well K. Satoh :Y. Yoneoka (*) Department of Neurosurgery, Brain Research Institute, Niigata University, 1-757 Asahimachi-dori, Niigata 951-8585, Japan e-mail: yone@bri.niigata-u.ac.jp