Show Notes
4.07 Polymyositis and Dermatomyositis MSK/Rheum review for the USMLE Step 1 Exam Polymyositis and dermatomyositis are autoimmune inflammatory myopathies. They are caused by abnormal activation of T cells that attack skeletal muscle and both cause proximal muscle weakness, especially of the shoulders and pelvic girdle muscles. Polymyositis develops when there is abnormal activation of CD8 T cells, while dermatomyositis is primarily attacked by CD4 T cells. Both are diagnosed through a muscle biopsy and the presence of elevated CK levels and several different autoantibodies. Dermatomyositis includes dermatologic manifestations, such as gottron papules, heliotrope rash, and shawl rash. Both are associated with MI, interstitial lung disease, and various types of cancer (dermatomyositis more so). Both diseases require prompt treatment with steroids and immunosuppressive agents.
More from Step 1 Basics (USMLE)
4.11 Antibody Review Rheumatology review for the USMLE Step 1 Exam. ANA Principles ANA (Anti-Nuclear Antibody): Non-specific antibody. Reacts against nuclear antigens, including proteins, DNA, RNA, and nucleic acid-protein complexes. Includes a group of antibodies such as anti-dsDNA, anti-histone, SSA/Ro, SSB/La, Scl-70, anti-aminoacyl-tRNA synthetase (Jo-1). Found in 20-30% of the general public without connective tissue disorder symptoms.
4.10 Gout and Pseudogout Rheumotology review for the USMLE Step 1 Exam. Gout Caused by uric acid crystal deposition due to purine metabolism. Triggers inflammation when crystals precipitate in cooler joint fluid. Presents with severe, red, and swollen monoarticular joints, often in the big toe. Diagnosis through synovial fluid analysis. Acute treatment: colchicine, NSAIDs, and glucocorticoids. Preventive treatment: allopurinol, febuxostat, probenecid, and lifestyle changes. Pseudogout Resulting from calcium pyrophosphate crystal deposition, often due to ATP breakdown. Manifests with painful, swollen joints, typically affecting multiple upper extremity joints, especially the knee. Diagnosis through synovial fluid analysis. Acute treatment resembles gout management. No direct preventive treatment to lower calcium pyrophosphate levels. Thanks for listening!
4.09 Rheumatologic Emergencies Rheumatology review for USMLE Step 1 Exam Giant Cell Arteritis (GCA) A large vessel vasculitis, mainly in older individuals. Symptoms: headache, jaw claudication, vision loss. Ischemia from granulomas in large vessels causes vision loss. Immediate high-dose corticosteroids are crucial. Scleroderma Renal Crisis A complication of scleroderma. Symptoms: finger edema, skin tightening, sudden hypertension, rising creatinine. Renal artery fibrosis leads to high blood pressure. Treat with IV ACE inhibitor, not steroids. Acute Transverse Myelitis in SLE Inflammation of the spinal cord in lupus. Symptoms: bilateral numbness, tingling, weakness. Treat with corticosteroids. Catastrophic Antiphospholipid Syndrome (CAPS) A rare, life-threatening form of APS. Symptoms: unexplained miscarriages, unexplained clots, multiorgan failure. Treat with anticoagulation followed by immune suppression
1.06 Systolic Heart Murmurs Cardiovascular system review for the USMLE STEP 1 Exam Heart murmurs are caused by turbulent blood flow in the heart
5.13 OCD and Related Disorders Psych review for the USMLE Step 1 Exam Obsessive Compulsive Disorder (OCD): Unwanted thoughts (obsessions) and repetitive behaviors (compulsions). Treat with CBT + SSRIs/SNRIs. Tic Disorders: Tourette Syndrome involves multiple motor and at least one vocal tic. Treat with Habit Reversal Therapy. Body Dysmorphic Disorder: Preoccupation with minor flaws, treat with SSRIs and CBT. Trichotillomania: Hair pulling disorder, treat with Habit Reversal Training and sometimes SSRIs. PANDAS: Pediatric disorder after strep infection, sudden OCD-like symptoms. Treat with antibiotics, CBT, and SSRIs.