Abstract:

A 61-year-old female presented with a 4-year history of eyelid swelling and pain. She had a subtle, yellow infiltrative plaque of the right upper and lower eyelid. Biopsy showed foamy histiocytes, Touton giant cells, cholesterol clefts, lymphoplasmacytic inflammation, and prominent necrobiotic collagen consistent with necrobiotic xanthogranuloma. Studies for monoclonal protein were negative. MRI and PET/CT showed involvement of periorbital soft tissues and ocular muscles, lacrimal gland, and cervical lymph nodes. Lymph node biopsy showed reactive follicular hyperplasia and flow cytometry was unremarkable. Treatment with intravenous immunoglobulin and rituximab is anticipated. The histologic and clinical differential of adult orbital xanthogranulomatous disease (AOXGD) includes necrobiotic xanthogranuloma (NXG), adult onset xanthogranuloma (AOX), adult-onset asthma and periocular xanthogranuloma (AAPOX), and Erdheim-Chester disease (EDC). These entities are characterized by infiltrating xanthomatized histiocytes with Touton giant cells. NXG has extensive necrobiosis on histology and is associated with paraproteinemia and hematologic malignancy. AOX has a predominance of Touton giant cells among lymphocytic inflammation. It is self-limited, not associated with underlying disorders, and usually unilateral. AAPOX is histologically like AOX with the densest lymphoid aggregates among these entities. AAPOX can infiltrate the anterior orbit and is associated with asthma, paraproteinemia, and lymphadenopathy. On histology, EDC exhibits the most fibrosis. EDC presents as diffuse bilateral xanthomas and can cause infiltration and fibrosis of internal organs, which can be fatal. Assessment for BRAF-V600E mutations or sequencing for BRAC-V600E, MAPK-ERK, and PI3K-AKT pathways should be considered. Distinguishing between these disorders is challenging, making the combination of histology, clinical history, and evaluation for underlying disorders paramount for diagnosis.

Financial Disclosure:
No current or relevant financial relationships exist.

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Colleen Morken, MD, MPH