What Are Amyloid Plaques?

Amyloidosis is the general term for a group of diseases with common characteristics and different clinical manifestations due to the abnormal deposition of amyloid proteins outside the cells of tissues and organs. This group of diseases can be divided into systemic amyloidosis and localized amyloidosis according to the extent of the affected area. Systemic amyloidosis is classified into primary, secondary, hereditary, and senile types. Localized amyloidosis is classified as skin, nodular, secondary, endocrine, and hereditary. When amyloid is deposited in normal skin, it is called primary skin amyloidosis, and when it is deposited in the lesion of skin disease, it is called secondary skin amyloidosis. Primary systemic amyloidosis mainly involves mesenchymal tissue. Accompanied by skin damage, secondary systemic amyloidosis mainly affects parenchyma of the whole body, especially liver, spleen, kidney, etc., without skin damage. The most common skin manifestations are primary skin amyloidosis and primary systemic amyloidosis.

Basic Information

Causes of skin amyloidosis

The etiology of amyloidosis is unclear. Primary systemic amyloidosis often has skin damage. Secondary systemic amyloidosis can be secondary to chronic inflammation and tumors, mainly involving parenchymal organs, without skin damage. Some Amyloidosis is related to heredity, so it is called hereditary amyloidosis, which can be combined in some syndromes.

Clinical manifestations of skin amyloidosis

1. Primary skin amyloidosis (1) Mossy amyloidosis is most common and occurs in middle-aged people. Skin lesions are distributed symmetrically on the extremities of the extremities. Typical skin lesions are hemispherical, polygonal, or cone-shaped. It has a hard papules with black horn plugs at the top. The skin lesions are dense and not fused. The calf and upper back rash are characterized by rosary formation along the skin lines.
(2) Patchy amyloidosis is more common in middle-aged and older women. Skin damage is mainly seen in the back and interscapular area or the extremities of the extremities. It appears as clusters of brown or purple-brown spotted rashes of 1 to 3 mm in size, which form a mesh or Wavy appearance, consciously mild itching.
(3) Heterochromatic disease-like skin amyloidosis is rare, and skin damage is manifested as pigmentation with punctate white spots, often accompanied by mossy or spotted amyloidosis.
(4) Nodular amyloidosis This disease, also known as amyloidoma, is rare. Skin lesions are common in the face, trunk, and extremities, and they appear as single or multiple nodules or plaques with waxy luster.
(5) Anal metatarsal skin amyloidosis This disease manifests as anal and metatarsal pigmentation with mossy amyloidosis.
(6) Frictional amyloidosis. This disease is caused by long-term rubbing with hard objects such as nylon brushes to cause spot-like or mossy skin lesions.
2. Primary systemic amyloidosis This disease occurs in middle-aged and elderly people, and skin damage occurs in skin folds. The most common skin damage is purpura, petechiae, and periorbital purpura are characteristic skin damage. Other typical manifestations are giant tongue, hepatomegaly, edema, and carpal tunnel syndrome.

Skin amyloidosis test

1. Physical examination of various types of amyloidosis characteristic skin damage, such as moss-like amyloidosis on the calf and upper back along the skin lines in a rosary arrangement of rash, spotted amyloidosis may have fusion to form a network or ripple Brown or purple-brown spotted rash.
2. Nomland test Nomland test (Congo red test) is positive.
3. Histopathological examination Amyloid in amyloidosis of plaque and mossy skin is limited to the dermal papilla; amyloid in amyloidosis of the nodules is diffusely deposited in the dermis, subcutaneous tissue and blood vessel wall; It appears as amyloid deposits in the dermis and subcutaneous tissue, and can involve the exuding sweat glands and blood vessel walls.

Diagnosis of skin amyloidosis

Based on the characteristics of physical examination and skin damage, combined with histopathological examination of amyloid and its distribution, diagnosis can be made.

Differential diagnosis of skin amyloidosis

1. Differential diagnosis of primary skin amyloidosis (1) Chronic simple moss: The basic damage of this disease is a polygonal flat papules that fuse to form a typical lichenoid change with a smooth surface. The disease is more common in frictional areas such as the neck, elbow extension, and crotch region. Subjective itching was paroxysmal aggravation.
(2) Hypertrophic lichen planus: It is a verrucous hyperplasia and hypertrophic plaque. There are scattered flat papules around the periphery, usually purple or brown-red. After healing, there may be pigmentation or skin scars.
(3) Nodular prurigo: The skin lesions of this disease are scattered red-brown pea-sized hemispherical solid nodules with rough surfaces and thickened keratinization. Patients often have severe itching.
2. Differential diagnosis of primary systemic amyloidosis (1) Myxedema moss: for localized or systemic lichen pimples and scleroderma-like changes, histopathological examinations include fibroblast proliferation in the skin, acidic adhesion Polysaccharides are characterized by excessive deposition.
(2) Senile purpura: This disease is more common in malnourished elderly people. Skin lesions are common in the face and neck, the back of the hand, the forearm and the lower leg. The rash can occur spontaneously for several weeks. .

Skin Amyloidosis Treatment

Treatment can be oral antihistamines, Awei A and so on. It can also be applied topically with strong glucocorticoid preparations, phototherapy or calcipotriol ointment, but the effect is limited. Nodular types can be treated by surgical resection, electric burning, freezing, and CO2 laser treatment, which are easy to relapse. There is no satisfactory treatment for primary systemic amyloidosis.

Prognosis of skin amyloidosis

Primary skin amyloidosis is prone to recurrence, most of which do not affect health and have a good prognosis. Primary systemic amyloidosis has a poor prognosis and is mostly caused by heart failure and renal failure.