Adult-Onset Asthma With Periocular Xanthogranuloma (AAPOX) Associated With IgG4-Related Disorder: A Case Report and Review of Current Literature.

Adult-onset asthma with periocular xanthogranuloma (AAPOX) is a rare orbital xanthogranulomatous disease characterized by periocular yellow to orange cutaneous papules and nodules, usually associated with lymphadenopathy and adult-onset asthma. Immunoglobulin G4-related disease (IgG4-RD) is a systemic, immune-mediated condition of unknown etiology characterized by distinct histopathological features. Here, we report the rare case of a 57-year-old asthmatic woman who developed AAPOX concurrently with IgG4-RD, showing a favorable response to rituximab, along with a review of current literature. She presented with bilateral periorbital violaceous nodules and bilateral parotid swellings that had been present for the past seven years. Histopathological examination of the lower eyelid revealed Touton giant cells and foamy histiocytes, consistent with xanthogranuloma, while a biopsy from the left parotid swelling demonstrated features suggestive of IgG4-RD. A literature review using the keywords "IgG4RD", "AAPOX", "co-existence", and "association" identified 11 articles describing 17 cases with overlapping features. There was a male predominance, with a mean age of presentation of 49 years. Common ophthalmological findings included bilateral periorbital swelling with xanthelasma-like lesions. Systemic manifestations included asthma, involvement of the lacrimal and parotid glands, lymphadenopathy, and pancreatitis. Treatment with prednisone and rituximab proved effective in most reported cases. It remains uncertain whether these two entities represent a spectrum of a single disease or a nonspecific immunological overlap.