In nodular amyloidosis, the amyloid deposits are found in the dermis and subcutaneous fat and within the walls of blood vessels. Clinically, the condition presents as brownish-pink, waxy-appearing papules or nodules, occurring singly or in groups, most commonly on acral surfaces and the face. Involvement of the trunk, genitals, and extremities has also been reported. There can be telangiectasias or atrophy of the overlying epidermis.
Men and women are affected equally. The disease usually begins in middle age. Typically, the prognosis is quite good, although a small minority of people (less than 10%) progress to systemic amyloidosis. A significant number of cases of nodular amyloidosis have occurred in association with Sjögren syndrome. For this reason, a thorough history and physical examination as well as appropriate screening tests to exclude this autoimmune disease are necessary.
E85.9 – Other amyloidosis
733729003 – Primary localized cutaneous amyloidosis
Differential Diagnosis & Pitfalls
- Sarcoidosis – A disease chiefly of individuals of African descent, sarcoidosis, particularly when it occurs upon the face (lupus pernio), may mimic nodular amyloidosis. The distinction is quite clear by biopsy, as sarcoid is a granulomatous rather than depositional disease.
- Cutaneous pseudolymphoma / lymphocytoma cutis – This condition, caused by recapitulation of lymph node-like tissue in the skin, is easily distinguished by biopsy.
- Colloid milium – Acquired colloid milium presents on sun-exposed surfaces of elderly patients, while juvenile colloid milium occurs in young people. The disease may resemble nodular amyloidosis both clinically and histologically. Electron microscopy may be utilized to discriminate between the conditions.
- Leiomyoma – Often presents as agminated (clustered) lesions of smooth muscle on the face that characteristically cause pain when exposed to cold (because of contracture). Biopsy easily distinguishes between the two conditions.
- Epidermal inclusion cyst
- Pilar cyst
- Basal cell carcinoma – A ubiquitous, sun-induced, nonmelanoma skin cancer, common on the face of middle-aged to elderly individuals and often associated with a waxy appearance and telangiectasias, similar to nodular amyloidosis. The condition is easily distinguished by biopsy.
- Tumor stage mycosis fungoides – Cutaneous T-cell lymphoma is easily distinguished from nodular amyloidosis on biopsy. Lesions of cutaneous T-cell lymphoma are more likely to ulcerate than nodular amyloid.
- Fibrotic stage of erythema elevatum diutinum