You are in: eMedicine Specialties > Dermatology > METABOLIC DISEASES Amyloidosis, LichenArticle Last Updated: Mar 7, 2007AUTHOR AND EDITOR INFORMATIONSection 1 of 8
  Author: Sultan Al-Khenaizan, MBBS, FRCP(C), Consulting Staff, Departments of Dermatology and Internal Medicine, King Fahad National Guard Hospital, Saudi Arabia Editors: C Lisa Kauffman, MD, FACP, Professor, Chief, Division of Dermatology, Departments of Medicine and Pathology, Georgetown University Medical Center; Richard P Vinson, MD, Assistant Clinical Professor, Department of Dermatology, Texas Tech University School of Medicine; Consulting Staff, Mountain View Dermatology, PA; Warren R Heymann, MD, Head, Division of Dermatology, Professor, Department of Internal Medicine, University of Medicine and Dentistry of New Jersey; Joel M Gelfand, MD, MSCE, Medical Director, Clinical Studies Unit, Assistant Professor, Department of Dermatology, Associate Scholar, Center for Clinical Epidemiology and Biostatistics, University of Pennsylvania; William D James, MD, Paul R Gross Professor of Dermatology, University of Pennsylvania School of Medicine; Vice-Chair, Program Director, Department of Dermatology, University of Pennsylvania Health System Author and Editor Disclosure Synonyms and related keywords: lichen amyloidosis, LA, amyloid deposits, multiple endocrine neoplasia type 2A, MEN 2A, Sipple syndrome INTRODUCTIONSection 2 of 8
  BackgroundAmyloidosis is a generic term that signifies the abnormal extracellular tissue deposition of one of a family of biochemically unrelated proteins that share certain characteristic staining properties, including apple-green birefringence of Congo red–stained preparations viewed under polarizing light. Under electron microscopy (EM), amyloid deposits are composed of linear, nonbranching, aggregated fibrils, 7.5-10 nm thick of indefinite length arranged in a loose meshwork. X-ray diffraction crystallography and infrared spectroscopy revealed that these fibrils have a meridional, antiparallel, beta-pleated sheet configuration with polypeptide chains arranged perpendicular to the long axis of the fibrils. Amyloid deposits contain (in addition to the fibrillar component) a nonfibrillar protein referred to as amyloid-P (Am-P). This protein is identical to normal plasma globulin, known as serum amyloid-P (SAP). Am-P constitutes 14% of the dry weight of amyloid. This protein is also found in the microfibrillar sheath of elastic fibers. SAP is closely related to the acute phase reactant C-reactive protein (CRP) and has been shown to be an elastase inhibitor. SAP and the beta-pleated sheet configurations are thought to protect amyloid deposits from degradation and phagocytosis, leading to persistence of the deposits. Lichen amyloidosis (LA) has been reported in association with few syndromes. The most intriguing is the association with multiple endocrine neoplasia type 2A (MEN 2A), also known as Sipple syndrome. The cardinal triad of this autosomal dominant syndrome is medullary thyroid carcinoma, pheochromocytoma, and hyperparathyroidism. Many cases of familial LA were reported in families with MEN 2A. The LA in this syndrome is usually localized to the interscapular region consisting of lichenoid papules, with hyperpigmentation and fine scaling. The histopathologic and immunohistochemistry findings are similar to those in isolated LA, pointing to keratin-derived amyloidosis. A single case of LA in Alagille syndrome has been reported. This consists of interlobular biliary duct deficiency and cardiovascular, vertebral, and ocular anomalies. The disease is associated with marked pruritus secondary to cholestasis. This is believed to be the cause of the amyloid deposition. PathophysiologyAmyloid deposits in macular and lichen amyloidosis bind to antikeratin antibodies. These deposits contain sulfhydryl groups, pointing to altered keratin as a source for these deposits. Apaydin et al found no differences in staining characteristics of cytokeratins between macular amyloidosis and LA. Interestingly, in their study, all the cytokeratins detected in amyloid deposits were of basic type (type II). This may be because, in amyloidogenesis, acidic cytokeratins such as cytokeratin 14 are degraded faster than basic types. Weyers et al presented a convincing argument that the deposition of amyloid in LA is not the cause but the result of itching and scratching. This argument was based on several lines of evidence. Amyloid deposition per se does not cause itching. Systemic amyloidosis is not associated with pruritus. Nonpruritic LA has also been described. Pruritus usually precedes the development of LA by years. Amyloid cannot be detected in clinically healthy skin of patients with LA. Striking similarities, both clinically and histopathologically, exist between LA and lichen simplex chronicus (LSC). RaceLA is believed to be more common in persons of Chinese ancestry than in other people. SexLA is more common in males than in females. AgeLA occurs most frequently in persons aged 50-60 years. CLINICALSection 3 of 8
HistoryTypically, LA is an intensely itchy eruption. PhysicalLA presents as intensely pruritic, red-brown hyperkeratotic papules most commonly seen on the pretibial surfaces, but it can also occur on the feet and the thighs. CausesSee Pathophysiology. DIFFERENTIALSSection 4 of 8
Lichen Sclerosus et Atrophicus Prurigo Nodularis
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| Drug Name | Chlorpheniramine (Chlor-Trimeton) |
|---|---|
| Description | Competes with histamine or H1 receptor sites on effector cells in blood vessels and respiratory tract. |
| Adult Dose | 4 mg PO q4-6h; not to exceed 24 mg/d |
| Pediatric Dose | <6 years: Not recommended 6-12 years: 2 mg PO q4-6h; not to exceed 12 mg/d >12 years: Administer as in adults |
| Contraindications | Documented hypersensitivity; asthma attacks; narrow-angle glaucoma; symptomatic prostate hypertrophy; bladder neck obstruction; stenosing peptic ulcer |
| Interactions | CNS toxicity increases with coadministration of other CNS depressants, tricyclic antidepressants, MAOIs, and phenothiazines |
| Pregnancy | B - Usually safe but benefits must outweigh the risks. |
| Precautions | May cause significant confusional symptoms; not for administration to premature or full-term neonates; drowsiness, dizziness, and dryness of mouth are the most common adverse effects; patients should not operate vehicles or hazardous machinery |
| Drug Name | Diphenhydramine (Benadryl) |
|---|---|
| Description | For symptomatic relief of symptoms caused by release of histamine in allergic reactions. |
| Adult Dose | 25-50 mg PO tid/qid |
| Pediatric Dose | <10 kg: Not established >10 kg: 12.5-25 mg PO tid/qid or 5 mg/kg/d PO divided tid/qid; not to exceed 300 mg/d |
| Contraindications | Documented hypersensitivity; MAOIs |
| Interactions | Potentiates effect of CNS depressants; because of alcohol content, do not give syr dosage form to patient taking medications that can cause disulfiramlike reactions |
| Pregnancy | C - Safety for use during pregnancy has not been established. |
| Precautions | May exacerbate angle-closure glaucoma, hyperthyroidism, peptic ulcer, or urinary tract obstruction; drowsiness, dizziness, and xerostomia are the most common adverse effects; patients should not operate vehicles or hazardous machinery |
This agent is an industrial solvent.
| Drug Name | Dimethyl sulfoxide (Rimso-50) |
|---|---|
| Description | May help relieve symptoms. DMSO, an oxidation product of dimethyl sulfide, is an exceptional solvent possessing a number of commercial uses. Not an FDA-approved indication. |
| Adult Dose | 50% solution in water applied topically over affected area |
| Pediatric Dose | Not established |
| Contraindications | Documented hypersensitivity |
| Interactions | None reported |
| Pregnancy | C - Safety for use during pregnancy has not been established. |
| Precautions | Garliclike breath odor and taste in the mouth due to excretion of small amount of DMSO as dimethyl sulfide (usually lasts only 24-48 h) |
Article Last Updated: Mar 7, 2007
