Primary cutaneous amyloidosis is caused by the deposition of amyloid material in the skin. Amyloid is a globulin and mucopolysaccharide complex, named for its starch-like chemical reaction such as iodine reaction, but actually has nothing to do with starch. It has been proposed that the disease is inherited in an autosomal dominant manner, and in some cases the abnormalities of lipids and proteins in the blood are thought to be related to metabolic disorders. Some patients have a family history. There are more males than females, and it is mostly seen in young adults, which can be prolonged for several years or decades. Etiology The products of amyloid and the reasons for its deposition in tissues are not known, and the etiologic mechanisms may differ in different biochemical types of amyloidosis, e.g., secondary amyloidosis is characterized by an impaired metabolism of the protein precursors (acute-phase reactant plasma amyloid A), whereas hereditary amyloidosis presents with different proteins, and in primary amyloidosis, a monoclonal population of myeloid cells produces proteins that are capable of form fragments or entire long chains of amyloidosis, Under the light microscope, amyloid is homologous, high-affinity, and has an affinity for Congo red dye in fixed tissues, and under the electron microscope it consists of 100 Å (10 nm) linear unbranched fibers, and under X-ray diffraction, it is crossed beta lines. The three main systemic clinical forms are now generally recognized; when amyloidosis is unrelated to disease it is termed primary or sudden (AL form), and when related to chronic disease it is termed secondary, acquired or reactive, which is either infectious (tuberculosis, bronchiectasis, osteomyelitis, leprosy) or inflammatory (rheumatoid arthritis, granulomatous ileitis), and amyloidosis has also been associated with multiple myeloma. Hodgkin's disease (AA), other tumors and familial Mediterranean fever. Type III, which occurs in families, is not associated with other diseases. In primary amyloidosis, the heart, lungs, skin, tongue, thyroid and intestines are often involved, and restricted masses are found in the respiratory tract and elsewhere. Substantial organs (liver, spleen, kidneys) and the cardiovascular system, especially the heart, are often involved. Secondary amyloidosis shows involvement of the spleen, liver, kidneys, adrenal glands, and lymph nodes. Although there are few clinical signs of cardiac involvement, the cardiovascular system is often extensively involved, the kidneys are often enlarged, and the liver and spleen are often enlarged with a hard, rubbery texture. As the normal splenic vesicles are replaced by white amyloidosis, the spleen enlarges and becomes translucent and waxy, known as the "sago" spleen. Hereditary amyloidosis is characterized by peripheral sensory and motor nerve (often autonomic) and cardiovascular and renal amyloidosis. Carpal tunnel syndrome and vitreous irregularities are often present. Amyloidosis associated with certain malignant diseases (e.g., multiple myeloma) has the same distribution as idiopathic amyloidosis; amyloidosis associated with other malignant diseases (e.g., medullary thyroid tumor) is associated only with the tumor or its metastases. Diabetes mellitus of adult onset is often found with amyloidosis in the pancreas. Symptoms and signs Symptoms and signs are nonspecific, determined by the organs and systems involved, and are often masked by the primary disease, which is fatal before amyloidosis is suspected. The renal system is the most intensely manifested, with only mild proteinuria early in the course of the disease, progressing to generalized edema, hypoproteinemia, and massive proteinuria. Hepatic amyloidosis has hepatomegaly but rarely jaundice, with severe hepatomegaly (liver weight >7 kg). Liver function is often normal despite increased (rarely persistent) sodium sulfobromophthalein excretion and increased alkaline phosphatase, occasionally portal hypertension is present, esophageal varices and ascites. Skin lesions cause waxy or translucent changes. Small vessel amyloidosis causes purpura. Cardiac involvement is common, presenting with cardiac enlargement, refractory heart failure and common arrhythmias. Atrial arrest has been found in several pedigreed family lines. GI amyloidosis causes abnormal esophageal dynamics, flaccid gastric tone, abnormal peristalsis of the large and small bowel, malabsorption, bleeding, or pseudo-obstruction. Tongue hypertrophy is common in primary or myeloma-associated amyloidosis. Harder texture, symmetrical, nonpalpable as in Hashimoto's thyroid disease or Riedel's thyroid disease due to amyloidosis of the thyroid gland, in rare cases of multiple myeloma, amyloid arthropathy similar to rheumatoid arthropathy and rarely clinically manifest peripheral neuropathies and more often in familial amyloidosis and primary or myeloma-associated amyloidosis. Amyloidosis involving the lungs (mostly AL amyloidosis) is characterized by limited pulmonary nodules, tracheobronchial lesions or extensive alveolar deposits. Clinical manifestations 1. It is common in young adults, with a chronic course and self-consciousness of severe itching; 2. The lesions are cornified keratinized domed papules with black keratinous plugs at the top. Hemispherical or polygonal, skin color or brown, surface roughness, peeling off the keratin plugs to see the umbilical depression; 3. Preferred in the extension of the calf, followed by the back, behind the ears, the lateral arm; 4. Occurred in the back, often reticulate pigmented spots. Diagnostic basis Based on the described symptoms, signs and symptoms, a primary diagnosis of amyloidosis can be made, and the diagnosis can only be confirmed by biopsy. Subcutaneous abdominal fat pad aspiration and rectal mucosal biopsy are the most commonly used screening methods, and other useful biopsy sites are the gums, skin, nerves, kidneys and liver. Green birefringent features of amyloidosis can be observed under a polarizable microscope in tissues stained with Congo red. A scintigraphic test with isotope-labeled serum AP confirms the diagnosis of amyloidosis. The prognosis of amyloidosis depends on the success of the treatment of the primary disease. All types of renal amyloidosis have a poor prognosis, but with intensive symptomatic treatment (e.g., treatment of pyelonephritis), the patient remains relatively stable, and dialysis and renal transplantation further improve the prognosis. Amyloidosis associated with multiple myeloma has the worst prognosis, with death occurring within 1 year of age. Restricted amyloid masses can be removed without recurrence, but cardiac amyloidosis is the most common cause of death, mainly due to arrhythmias or refractory heart failure. The prognosis of familial amyloidosis varies by family lineage. Treatment Treatment begins with preventing amyloidosis from developing by targeting the primary disease, amyloidosis itself is treated symptomatically, patients with renal amyloidosis can undergo renal transplantation, survival is longer than other kidney diseases but mortality is higher in the early stages, amyloidosis will eventually recur in the donor kidney but some transplants can survive up to 10 years. Common treatment plans for primary amyloidosis include prednisone/mefaram or prednisone/mefaram/colchicine, and clinical trials are underway to compare these treatment plans. Stem cell transplant programs are controversial. Digitalis may be used with caution in patients with amyloid heart disease who may develop arrhythmias. Heart transplantation has been successful and requires rigorous patient selection. Colchicine is used to prevent acute exacerbations in patients with familial Mediterranean fever and has shown no new amyloid appearances and a downward trend in amyloidosis after treatment. Treatment of hereditary amyloidosis with the application of transformed transthyretin and liver transplantation to remove the site of synthesis of mutant proteins has been very effective. [