Subfoveal Choroidal Thickness in Patients with Histiocytosis and Multimodal Imaging Features of Choroidal Infiltrates.

Purpose: To evaluate choroidal findings in patients with histiocytosis including subfoveal choroidal thickness (SFCT), and multimodal imaging in eyes with choroidal infiltrates visible by ophthalmoscopy; and to determine if abnormalities change with histiocytosis-directed (kinase inhibitor) therapy.

Participants: 91 patients with histiocytosis and 41 age- and gender-matched controls.

Design: Retrospective comparative study at single tertiary cancer referral center.

Methods: Clinical exam, fundus photography and OCT were used to assess choroidal findings. Clinically evident choroidal infiltrates by ophthalmoscopy were recorded and choroidal vascular architecture was qualitatively examined. SFCT and was measured using enhanced depth imaging spectral domain optical coherence tomography (EDI SD-OCT) from the outer portion of Bruch's membrane to the choroidal scleral interface.

Main outcome measure: SFCT compared to matched controls; secondary outcome was change in SFCT on histiocytosis-directed (kinase inhibitor) therapy. Multimodal imaging of choroidal infiltrates visible by ophthalmoscopy.

Results: One hundred and eighty two eyes of 91 patients (46 males, 45 females) with histiocytiosis (Erdheim-Chester 35, Rosai-Dorfman 21, Xanthogranuloma 7, Mixed histiocytosis 11, Langerhans cell histiocytosis 15 and other 2) were examined. In histiocytosis patients, the mean SFCT was 336.2 +/- 94.9 μm compared with 250.3 +/- 60.7μm in the control group (p<0.0001). 69% of histiocystosis patients had SFCT > 275μm compared to 27% in controls (p< 0.0001). Subtype of histiocytosis, sites of bone or central nervous disease, posterior segment/other sites of ophthalmic disease, or mutational profile did not correlate with SFCT. In a subgroup analysis of 35 patients naïve to prior treatment, with > 6 mos follow-up, the proportion of SFCT > 275 μm significantly decreased (p-value = 0.0016) on histiocytosis-directed (kinase inhibitor) therapy. 19.8% of patients had clinically evident choroidal infiltration: majority were yellow creamy, geographic, located posteriorly and hyperautofluorescent; with enlarged Haller's vein bordering the infiltrate, choriocapillaris compression and loss of choroidal architecture by OCT.

Conclusions: In this cohort, 19.8% of histiocytosis patients had clinically evident infiltration of their choroid. Furthermore, the majority of patients with histiocytosis had increased subfoveal choroidal thickness compared with age- and gender-matched controls. The thickened choroid decreases on histiocytosis-directed (kinase inhibitor) therapy and may be a marker of response to systemic treatment.