Necrobiotic Xanthogranuloma: Diagnosis, Genetic Mimics, and Emerging Treatments

Conclusions

• Necrobiotic xanthogranuloma is best understood as a granulomatous xanthomatous disorder strongly associated with paraproteinemia and hematologic malignancy, so long-term surveillance is essential.
• The validated Delphi diagnostic criteria appear to reliably identify NXG, but diagnosis now requires careful clinicopathologic correlation rather than histology alone.
• The eye is the most important extracutaneous site in NXG, making ophthalmology referral a key part of evaluation.
• Laboratory patterns in NXG can include low HDL, low complement, cryoglobulins, and atypical vitamin D abnormalities, which may help support the diagnosis and guide workup.
• Treatment evidence for NXG is limited, but IVIG currently appears to have the highest overall response rate among reported therapies.
• JAK inhibitors may be a promising option for refractory NXG, though their use must be weighed against infectious, thrombotic, and malignancy risks.
• A newly recognized genetic mimic of NXG is sitosterolemia due to ABCG5/ABCG8 variants, which can fulfill NXG-like criteria and should prompt genetic testing in the right clinical setting.
• Patients with NXG-like lesions plus macrothrombocytopenia, anemia, arthralgia, premature atherosclerosis, and no paraprotein should be evaluated for sitosterolemia.
• Some cases previously labeled NXG may be retrospectively reclassified as sitosterolemia, suggesting that NXG may not be a single uniform disease entity.
• Overall, the presentation argues for a broader diagnostic approach that combines skin findings, hematologic screening, eye examination, and selective genetic testing to avoid misclassification and improve management.