1. GVHD: 
- Skin is most commonly affected organ - next GI tract, liver
- Causes itchy maculopapular rash that often starts on palms and soles
- Skin may blister and even ulcerate
- Most commonly occurs after hematopoetic stem cell transplant (can even occur after blood transfusion in people who don't have T-cells or getting transfusions from close relatives - see June 15 2014 blog post about transfusion related GVHD and for a detailed description of all transfusion reactions) can rarely occur after solid organ transplant
- Treat with IV steroids to suppress engrafted T-cells
2. Dermatitis herpetiformis responds so quickly to dapsone (2-3 days) that a response is considered diagnostic
3. Erythema nodosum: 
- Inflammatory reaction of fat cells
- causes tender, inflamed nodules of shins
- Most common causes - idiopathic (50%), infectious (25%) (strep throat, mycobacteria, mycoplasma, the systemic fungal infections we learn about (histo, coccidioides) chlamydia, yersenia, rickettsia), sarcoid 25%, drugs (rare <5% OCPs, sulfa drugs, amoxicillin), IBD (<5%), pregnancy (<5%)
- Mnemonic for causes: "sore shins"
Sarcoid
OCPs
Rickettsia
Eponyms - like behcets
Sulfa drugs
Hansen's disease (leprosy)
IBD
NHL - non hodgkin's lymphoma
Strep
- Treat underlying cause. manage symptoms (bedrest, leg elevation, compressive bandages, wet dressings). NSAIDs work best in early phase, K-iodide in late phases.
4. Pyoderma gangrenosum: 
- Altered neutrophil chemotaxis
- Deep, nonhealing ulcers of legs (can affect hands - atypical pyoderma gangrenosum) with rolled violet edges
- Display pathergy- worse with debridement
- Associated with IBD, RA, seronegative spondyloarthritis, AML
- Treat with nsaids, steroids, biologics, antibiotics
- Good prognosis, frequent recurrence.
5. Acute promyelocytic leukemia - aka M3 subtype of AML. Responds well to all-trans retinoic acid. Can cause rapid death via DIC. Can also use retinoic acid with 5-FU to treat actinic keratosis.
6. Timing of repeat colonoscopy:
- At 3 years = high risk colon polyps: >1cm, high grade dysplasia, villous features, >3 adenomas
- At 5 years = low risk colon polyps: <1cm, low grade dysplasia, tubular adenomas, 1-2 polyps
- At 10 years = everyone else. Small hyperplastic polyps, esp in rectum.
7. Dieulafoy's lesion - large tortuous arteriole in stomach that can rupture and cause massive gastric hemorrhage - these are thought to be a congenital vascular malformation rather than degenerative.
8. Benzos safe in hepatic insufficiency: oxazepam, lorazepam
9. Steroids convey a survival benefit in severe alcoholic hepatitis 
- Contraindications: acute infection (SBP/sepsis), GI bleed, renal failure - this one I don't understand. The reasoning is not clear to me... steroids are primarily hepatically metabolized, although there is a renal metabolism component - 11-OH BSD converts cortisol to inactive cortisone, and prevents it from hitting mineralcorticoid receptors too hard. Perhaps that is the rationale... in acute hepatitis perhaps the renal metabolism becomes more important. Although it is unclear to me how much synthetic or metabolic function is lost in acute hepatitis.
This little ditty in the AJG suggests that there was some thought that steroids are not effective in the management of acute hepatitis when there is concomitant hepato-renal syndrome, but at least in this short case it seemed to help....
10. Dietary causes of osmotic diarrhea: 
- Lactose/fructose intolerance
- Excessive ingestion of magnesium, vitamin C