DERMATOLOGY FOR THE USMLE AUTOIMMUNE SKIN DISORDERS (2) 1. SYSTEMIC SCLEROSIS (SCLERODERMA)

DERMATOLOGY FOR THE USMLE

AUTOIMMUNE SKIN DISORDERS (2)

1. SYSTEMIC SCLEROSIS (SCLERODERMA)

→	General: Complex, multifactorial autoimmune systemic disease of unknown etiology characterized by abnormal collagen deposition in different organs. Overproduction of transforming growth factor beta (TGF-β) is thought to play an important role in the pathogenesis. It is a female predominant disease with an average age of onset between age 30 to 50. Major organs affected are: » Lungs: Interstitial lung disease (fibrosis) and pulmonary hypertension (lung disease is the most common cause of death). » Kidney: Renal failure and hypertension (renal crisis). » Vascular: Raynaud, ischemia (ulcers) and telangiectasias. » Heart: Pericarditis, restrictive cardiomyopathy and arrhythmias. » Musculoskeletal: Myalgias, weakness and arthralgia. » GI tract: Dysphagia (esophageal dysmotility), chronic GERD (immobile esophageal sphincter), diarrhea, bloating and vitamin B12 deficiency (small intestine bacterial overgrowth secondary to GI dysmotility)
→	Clinical: Subdivided into diffuse and limited systemic sclerosis. » Diffuse Systemic Sclerosis: Worst prognosis; progressive disease that may affect any of the organs listed above. Commonly starts with Raynaud phenomenon, a vasospasm reaction to cold that causes fingers to turn white blue-red. The skin becomes firm, shiny and thickened resulting in marked skin tightness; when these cutaneous manifestations affect the fingers or toes, it is known as sclerodactyly These skin changes can result in limited mobility, flexion contractures and loss of facial expression Digital ulcers commonly develop secondary to poor vascular circulation. The skin may have a mixture of hyper- and hypopigmentation and permanent scarring may occur in late stages. » Limited Systemic Sclerosis (CREST syndrome): Rarely involves internal organs, it is characterized by: Calcinosis Raynaud phenomenon Esophageal dysfunction Sclerodactyly Telangiectasias
→	Diagnosis » Best initial test: Clinical + autoantibody assays to detect anti-nuclear antibody, anti-topoisomerase I (anti-Scl-70) and anti-centromere (CREST syndrome). Depending on initial presentation, consider any of the following tests: Lung: High-resolution chest CT scan and pulmonary function tests (PFTs). Kidney: Renal function tests (BUN and Cr). Heart: Echocardiography and ECG. GI tract: Esophageal manometry and gastric emptying studies. » Most accurate test: Skin biopsy showing epidermal atrophy and intense collagen deposition in dermis with sclerosis and loss of fat around adnexal structures.
→	Treatment » First line: Raynaud phenomenon: Calcium channel blockers (eg, nifedipine). Pulmonary hypertension: Prostacyclin analogues (eg, epoprostenol) or endothelin antagonists (eg, bosentan). Renal crisis: ACE inhibitors (eg, captopril). Interstitial lung disease (ILD): Cyclophosphamide or mycophenolate mofetil. GI tract: PPIs for GERD, metoclopramide for GI dysmotility and antibiotics for small intestine bacterial overgrowth. » Second line: Systemic therapy with steroids, methotrexate or D penicillamine for severe disease.
→	USMLE Pearls: raynaud phenomenon: Divided into primary and secondary Raynaud phenomenon. Primary Raynaud (Raynaud disease) occurs idiopathically without an associated underlying medical condition. Secondary Raynaud, commonly referred to as Raynaud phenomenon, is associated with an underlying systemic disease such as scleroderma or SLE. To distinguish between the two, perform a nailfold capillaroscopy. This test is done by placing a drop of oil on the fingernail an observing it closely with a dermatoscope. An abnormal nail arterial pattern is a positive test and means that the patient has secondary Raynaud.