Necrobiotic xanthogranuloma (NXG) is a rare histiocytic disorder that presents as firm yellow papules and plaques of the skin, most often in the periorbital area. It is strongly associated with an immunoglobulin G (IgG) monoclonal gammopathy (80%-90% of cases), particularly IgG kappa (60%). NXG may affect extracutaneous tissues including the eye, spleen, heart, lung, kidney, intestine, ovary, larynx, pharynx, skeletal muscle, and central nervous system. Ophthalmologic complications occur in about 50%-80% of patients, and may include orbital masses, conjunctival involvement, keratitis, scleritis, and uveitis.
In a 2020 multicenter study and systematic review of 235 cases of NXG, the mean age at presentation was 61.8 years with a 3:2 female to male predominance.
NXG often follows a protracted and indolent course, but patients with the condition also have an increased risk of plasma cell dyscrasias (multiple myeloma and monoclonal gammopathy of undetermined significance [MGUS]) and other lymphoproliferative disorders. When these coexisting conditions exist, the disease may follow a fatal course.
The etiology of NXG is unknown. It is speculated that the paraprotein, present in the majority of cases, binds to lipoprotein receptors of monocytes, inducing formation of a xanthogranuloma, or may bind to serum lipoproteins.
Necrobiotic xanthogranuloma
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Synopsis
Codes
ICD10CM:
D76.3 – Other histiocytosis syndromes
SNOMEDCT:
404164003 – Necrobiotic xanthogranuloma
D76.3 – Other histiocytosis syndromes
SNOMEDCT:
404164003 – Necrobiotic xanthogranuloma
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Differential Diagnosis & Pitfalls
The clinical differential diagnosis for NXG may include:
- Necrobiosis lipoidica – More common in diabetic patients and nearly always occurs on the pretibial area; this condition does not have an association with paraproteinemia.
- Granuloma annulare – Classically occurs as annular lesions without scale; usually erythematous, without the yellow color seen in NXG.
- Xanthelasma – Occurs as thin yellow plaques, most often near the inner canthus of the eyelid, more often on the upper lid than the lower lid. Xanthelasma, in contrast to NXG, is usually thin and soft, without extension into the orbit or other ocular symptoms.
- Normolipemic plane xanthoma – Yellow macules or thin plaques that may also be associated with monoclonal gammopathy but usually occur on the neck, flexural areas, and less often on the face.
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Last Reviewed:05/31/2020
Last Updated:06/01/2020
Last Updated:06/01/2020
Necrobiotic xanthogranuloma