8.13 Disorders with primary and secondary deposition in the skin
Grading & Level of Importance: C
Amyloidosis, Mucinosis, Myxoedema, Hyalinosis, Xanthoma/Xanthelasma, Gout/Hyperuricaemia, Calciphylaxis, Tattoo.
These are rare diseases. AL amyloidosis occurs in about 3–13 per million people per year.
Disorders with primary and secondary deposition in the skin are a heterogenous group of diseases, characterized by the pathological accumulation of materials in the extracellular matrix of the dermis or subcutis.
Aetiology & Pathogenesis
Primary localized cutaneous amyloidosis: idiopathic or mutations in the OSMR or IL31RA gene.
Secondary (AL) amyloidosis: light chain deposits that are produced by malignant plasma cells.
Mucinosis: thyroid disorders (myxoedema), lymphomas, inflammatory skin diseases.
Uric acid deposits (gout): idiopathic or linked to food excess.
Calciphylaxis: terminal chronic renal deficiency.
Skin calcinosis: connective tissue diseases.
Tattoos: trauma, voluntary intradermal pigment injection or deposition of dust and burnt substances.
Signs & Symptoms
Primary localized cutaneous amyloidosis: severely itchy patches of thickened, scaly and reddish-brown skin with multiple small bumps (lichen amyloidosis) or flat and dark brown patches (macular amyloidosis).
Secondary (AL) amyloidosis – vessel fragility with pinch purpura and periorbital purpura, unexplained bleeding or macroglossia.
Mucinosis – flat, shiny erythematous plaques.
Myxoedema – skin coloured flexible plaques, “orange peel” surface, pretibial location frequently, rarely hyperkeratosis.
Xanthoma/xanthelasma – small yellowish soft nodules, grouped.
Connective tissue disorders-associated calcinosis – rock hard subcutaneous nodules that may fistulate.
Calciphylaxis – skin necrosis with accompanying erythematous network like maculae (livedo), extremely painful.
Pathological tattoos – black, grey or brown macules of millimetric size, localized.
Primary localized cutaneous amyloidosis – lichen amyloidosis: extensor faces of the limbs, and macular amyloidosis: often interscapular.
Secondary (AL) amyloidosis – periorbital or at skin sites exposed to wear and tear/physical trauma.
Mucinosis – depends on the etiology.
Myxoedema – frequently pre-tibial.
Xanthelasma – peri-orbital.
Xanthoma – frequently over pressure points.
Calciphylaxis – fatty areas of the body (abdomen, flanks, buttocks, thighs, breasts in women).
Tattoos – anywhere.
Gout – hallux (also called podagra) or fingers (also called tophus).
Laboratory & other workups
Secondary amyloidosis – blood count, serum electrophoresis and immunofixation, kappa/lambda light chain measurement in blood, eventually bone marrow aspiration.
Myxoedema – thyroid hormones.
Xanthoma/xanthelasma – lipid profile.
Calciphylaxis – calcium, albumin, blood count, renal function.
Amyloidosis: congo red stain shows a green birefringence.
Gout: crystal depositions.
Xanthoma and xanthelasma: lipid deposits.
Mucinosis and myxoedema: mucopolysaccharides.
Slow progression followed by a stabilisation. The treatment remains difficult in most depositional skin disorders.
These diseases may progress if the underlying disease is not treated.
Clinical and histological.
Other forms of depositional disorders.
Prevention & Therapy
Treatment of the underlying disease.
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