DIP Episode 358 - USMLE Step 2CK/3 Rapid Review Series 68

Source / episode info

• Episode: 358
• Title: Divine Intervention Episode 358 – USMLE Step 2 CK/3 Rapid Review Series 68
• Published: 2021-12-21
• Source: Episode page

One-liner

This episode reviews high-yield topics including the management of toxoplasmosis in HIV patients, recognizing parvo-B19 induced aplastic crisis, managing varices secondary to alpha-1 antitrypsin deficiency and portal hypertension, diagnosing candidiasis, and understanding skin manifestations like tinea nigra.

High-yield summary

• Toxoplasmosis (HIV): Ring-enhancing brain lesions in an HIV patient are highly suggestive of Toxoplasma gondii. Treatment is Pyrimethamine + Sulfadiazine; use Spyramycin during pregnancy to avoid folate antagonism.
• Parvovirus B19: Causes aplastic crisis, particularly in patients with underlying hemolytic anemia (e.g., sickle cell disease). Key findings include reticulocytopenia and transient drop in hemoglobin. It can also cause hydrops fetalis due to chronic high cardiac output state.
• Portal Hypertension/Varices: Secondary to conditions like Alpha-1 Antitrypsin Deficiency leading to cirrhosis. Acute management involves IV fluids (Normal Saline preferred) and PP Is; prophylaxis requires Octreotide, beta-blockers (e.g., Spironolactone), and prophylactic antibiotics (SBP coverage).
• Candidiasis: Vaginal candidiasis is associated with a low vaginal pH ( 4.5) and wet prep showing pseudo-hyphae. Treatment preference on exams is topical/oral azoles, favoring Fluconazole over Nystatin due to side effects.
• Tinea Nigri: A pigmented skin lesion strongly linked to sun exposure (biggest risk factor). While most lesions resolve spontaneously, persistence can lead to Squamous Cell Carcinoma (SCC); remember that keratin pearls can be found in tinea nigra, not exclusively SCC.

Learning objectives

• Differentiate between opportunistic CNS infections (e.g., Toxoplasma gondii) in immunocompromised patients.
• Recognize the characteristic laboratory findings associated with Parvovirus B19 infection, particularly aplastic crisis.
• Understand the pathophysiology and management of portal hypertension complications arising from chronic liver disease (e.g., AATD).
• Master the clinical presentation and diagnostic criteria for common superficial fungal infections like candidiasis and tinea nigra.
• Correlate environmental risk factors (sun exposure) with specific dermatological conditions.

Board exam buzzwords

Rapid review table

Board-speak -> diagnosis

Differential diagnosis / distinguishing features

Skin Pigmentation Disorders

Variceal Bleeding/Portal Hypertension

Management pearls

• Varices Prophylaxis: For patients with portal hypertension (e.g., cirrhosis from AATD), the regimen includes: 1) Beta-blockers (Spironolactone); 2) Alpha-blocker (Carbidopa/Levosalpine); and 3) PP Is (for peptic ulcer prophylaxis).
• Acute Variceal Bleeding: Initial management involves IV fluids (Normal Saline is preferred), Octreotide (vasoconstrictor), and a Proton Pump Inhibitor (PPI).
• Candidiasis Treatment: While multiple azoles are available, Fluconazole is often the preferred choice in exam settings for systemic or severe localized infections due to better bioavailability compared to Nystatin.
• Aplastic Crisis Management: The primary treatment is supportive care and management of the underlying trigger (e.g., treating Parvovirus B19 infection). Transfusion may be necessary if anemia is life-threatening.

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Integration & clinical reasoning

• Infectious Disease & Immunosuppression: The management of opportunistic infections (like Toxoplasma) is highly dependent on the patient's immune status, requiring specific drug adjustments (e.g., Spyramycin during pregnancy).
• Genetics & Organ Failure: Alpha-1 Antitrypsin Deficiency demonstrates how a single genetic defect can cascade through multiple organ systems (lungs -> liver -> GI tract) leading to severe complications like portal hypertension.
• Dermatology & Environment: Skin findings are often dictated by environmental exposure; sun exposure is the primary risk factor for Tinea Nigri, linking dermatology back to preventative care.

OMM / COMLEX integration

• Standard emergency management for variceal bleeding/shock takes priority over OMT. However, the understanding of portal hypertension pathophysiology (increased splanchnic flow) provides context for why medications like Octreotide and beta-blockers are used to reduce portal pressure.
• The recognition of systemic infections (like Toxoplasma) requires a broad differential diagnosis that includes CNS involvement, which is relevant when considering potential sources of inflammation or abscesses in the abdomen/pelvis.

Concept connections / cross-references

• For detailed information on HIV management and opportunistic infections: Episode 184 (or similar episode covering infectious disease).
• For general principles of liver failure and portal hypertension: [Cross-reference relevant GI/Hepatology podcast].
• For understanding the pathophysiology of anemia and bone marrow failure: [Cross-reference Hematology podcast].

High-yield association table

Key terms glossary

Study optimization

Question pattern recognition

• Pattern: Ring-enhancing lesions in HIV patient -> Toxoplasma gondii Encephalitis. This is the most common cause; always assume it first.
• Pattern: Hemolytic anemia + Acute drop in reticulocytes after viral illness -> Parvovirus B19 infection causing aplastic crisis.
• Pattern: Cirrhosis secondary to AATD/Chronic Liver Disease with varices -> Prophylaxis requires a triple therapy approach (Beta-blocker, Alpha-blocker, PPI) plus Octreotide acutely.

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