Lecture 14 Part 2 PDF

Staph Scalded Skin Syndrome (SSSS) SSSS is uncommon. It is most prevalent in children under age 5. It can also occur in adults with renal failure and/or immunosuppression. SSSS often starts with a prodrome of fever and malaise. The skin may or may not be tender. Widespread erythema develops, then...

Staph Scalded Skin Syndrome (SSSS) SSSS is uncommon. It is most prevalent in children under age 5. It can also occur in adults with renal failure and/or immunosuppression. SSSS often starts with a prodrome of fever and malaise. The skin may or may not be tender. Widespread erythema develops, then flaccid bullae (often quite large) develop (Figure 14.18) and finally rupture. The skin that did not blister will slough off. There is fairly quick healing without scarring, and most children do very well. Adults have a higher risk of significant morbidity and mortality, largely because they tend to have significant underlying medical problems. SSSS is caused by an exfoliative toxin produced by certain strains of Staphylococcus aureus. This is the same toxin that causes bullous impetigo (see lecture 4). The toxin works by cleaving desmoglein 1, which causes the very superficial epidermis (stratum corneum) to detach from the underlying epidermis. Flaccid, fragile blisters can then form under the loose stratum corneum. Sometimes this superficial layer may directly slough without any blister forming. Adults are generally protected from SSSS for two reasons: 1) their kidneys filter the toxin, removing it before sufficient amounts can accumulate to cause clinical disease; 2) they have antibodies that bind to and neutralize the toxin. These likely developed during subclinical infections in childhood. In adults who have renal failure, circulating toxin cannot be removed. In adults with immunosuppression, the neutralizing antibodies may no longer be produced. Young children are at risk because of 1) decreased renal function relative to adults and 2) a naïve immune system lacking neutralizing antibodies. Treatment of SSSS mainly consists of antibiotics to kill the bacteria and prevent further toxin production. The lost skin layer is very superficial, so patients tend to heal very quickly without complications. Moist dressings and bland emollients should be applied to the skin to accelerate the healing process. Finally, good hygiene should be practiced to prevent infection. Adults with SSSS have a fairly poor prognosis, often due to the generally poor underlying health status. SSSS causes both impaired fluid regulation due to massively increased insensible losses through the skin and increased risk of infection due to altered skin barrier function, and these two issues are often enough to start a progressive decline in an already fragile patient. Vasculitis Vasculitis can be a very confusing topic in medicine for three main reasons: 1) vasculitis can present with almost any sign or symptom imaginable, so it is very frequently in differential diagnoses; 2) the term vasculitis refers both to a general pathologic finding (inflammation centered on blood vessels) and to many specific diseases; and 3) it is frequently difficult to make the diagnosis or to rule out the diagnosis. Vasculitis is usually grouped according to the largest vessels affected. Small vessel vasculitides affect capillaries, arterioles, and venules; medium vessel vasculitides affect small arteries and veins; large vessel vasculitides affect larger, named vessels. Small Vessel Vasculitis (SVV) The classic type of cutaneous SVV is leukocytoclastic vasculitis (LCV), and its primary cutaneous manifestation is “palpable purpura”. This refers to small (usually 1-10 mm), dark (purple-to-blue), papules that do not fade with pressure (Figure 14.19). In general, LCV is caused by deposition of immune complexes (antibody bound to antigen) in blood vessels. Any source of antigen to which antibodies develop can be causative. In about 50% of cases, a causative antigen is discovered (such as a drug, microorganism, or endogenous antigen in an autoimmune disease). In the other 50% of cases, the causative antigen is not discovered (“idiopathic LCV”). HSP is one specific type of LCV. After SVV is confirmed by biopsy, the evaluation of the patient should have two goals: 1) Looking for a causative antigen: at a minimum, this includes evaluation for chronic infections (hepatitis B and C, chronic endocarditis, chronic streptococcal infection, etc.), a thorough drug history (prescription, over-the-counter, herbals, etc.), and evaluation for autoimmune diseases (lupus, RA, Sjogren’s disease, etc.). 2) Looking for vasculitis in organs other than the skin: good review of systems (looking for neurologic symptoms (CNS vasculitis), visual symptoms (ocular vasculitis), abdominal pain or hemoccult+ (intestinal vasculitis), shortness of breath (lung involvement), muscle pain or weakness (muscle involvement), urinalysis (renal involvement), and LFTs (hepatic involvement). Other types of SVV are microscopic polyarteritis, Wegener’s, and Churg-Strauss. These are generally considered to be primary autoimmune diseases. 1) Microscopic polyarteritis (MPA): Often have significant systemic symptoms (fever, malaise, etc.). Frequently have glomerulonephritis. Less than 50% have cutaneous findings (similar to the findings in LCV). May have c-ANCA (cytoplasmic anti- neutrophil cytoplasmic antibodies) or p-ANCA (perinuclear-ANCA) on serologic testing. 2) Wegener’s Granulomatosis (WG): Classically involves the upper respiratory tracts (nose, pharynx, sinuses) with vasculitis. Significantly less than 50% have cutaneous findings (ulcers, nodules, necrosis). Most have c-ANCA. 3) Churg-Strauss Syndrome (CSS): Combination of asthma, eosinophilia, and vasculitis. Often have multi-organ vasculitis. Most have p-ANCA. Medium Vessel Vasculitis (MVV) MVV can have cutaneous manifestations such as ulcers and nodules (Figure 14.20). The classic MVV is polyarteritis nodosa (PAN). About half of patients with PAN have cutaneous findings, mainly necrotic nodules or ulcers. Most patients have significant systemic vasculitis (renal, neurologic, cardiac, intestinal), and many have hepatitis B. Some patients will have p-ANCA. In addition to PAN, the other significant forms of MVV are isolated CNS vasculitis and cardiac vasculitis in Kawasaki’s disease. Large Vessel Vasculitis (LVV) LVV typically do not have specific cutaneous manifestations. When present, they typically include necrosis and gangrene of fingers, toes, limbs, or significant portions of skin. The classic types are Takayasu’s arteritis and giant cell (a.k.a. temporal) arteritis. Typically, the definite diagnosis of vasculitis requires pathologic confirmation of vascular inflammation via a biopsy of affected tissue. This is relatively simple with cutaneous involvement, but can be quite difficult if only internal organs are involved. Both serologic studies (ANCAs, etc.) and radiologic studies looking at the vasculature can suggest the diagnosis. Radiologic studies can also help determine the best site if an internal organ (intestinal tract, brain, kidney, etc.) needs to be biopsied. Leukocytoclastic vasculitis (LCV) is usually a relatively straightforward diagnosis – a skin biopsy of a cutaneous lesion will confirm the diagnosis. The challenge comes in looking for a cause of the vasculitis and identifying any systemic involvement. In the other forms of vasculitis, the challenge lies in making the diagnosis. In the other forms of small vessel vasculitis (MPA, WG, CSS), medium vessel vasculitis (PAN, CNS vasculitis), and large vessel vasculitis, the patients often present with relatively non-specific complaints and findings (shortness of breath, abdominal pain, fevers, myalgias, etc.). It is usually only after an extensive evaluation that the correct diagnosis is suspected, but often difficult to confirm, as obtaining a biopsy of affected tissue is frequently difficult. If a cause of LCV (drug, infection, etc.) can be identified, then treatment revolves around correcting the underlying cause. In idiopathic cases, treatment involves anti-inflammatory medications (systemic steroids) and immunosuppressive medications (systemic steroids, azathioprine, cyclosporine, etc). More severe cutaneous vasculitis requires more aggressive immunosuppression to adequately treat it. Most of the other vasculitides are considered primary autoimmune diseases. Treatment requires aggressive immunosuppression, often with multiple agents. Again, the aggressiveness of the immunosuppression is correlated with the severity of the disease and the risk of significant compromise of organ function by the vasculitis. Calciphylaxis Calciphylaxis is uncommon, but not rare. It occurs almost exclusively in chronic renal failure. Calciphylaxis presents as extremely painful violaceous patches, which relatively quickly become necrotic, and often turn into dry, black eschars overlying superficial ulcers. The legs are the most commonly involved areas, but the trunk may also be involved. Involvement of the trunk and/or proximal extremities portends a worse prognosis than exclusive involvement of the distal limbs. Calciphylaxis results from calcification and thrombosis of the small, subcutaneous arteries and arterioles, which impairs blood flow to the skin and subcutaneous tissue, leading to ischemia and eventual tissue death. Many patients with chronic renal failure develop secondary hyperparathyroidism as a result of abnormal calcium metabolism and vitamin D production. This leads to further alterations in the homeostasis of calcium and phosphorus. It is hypothesized that calciphylaxis occurs as a result of increased calcium-phosphorus product. In patients with renal failure and secondary hyperparathyroidism, either the calcium or the phosphorus (or both) can be elevated. However, calcium and phosphorus levels are usually normal in patients hospitalized with calciphylaxis. This does not mean, however, that they were normal a week ago, a month ago, or 6 months ago. Treatment of calciphylaxis is extremely difficult. If the calcium or phosphorus is elevated, they should be aggressively managed and brought to normal levels. If PTH is elevated (i.e., if they have secondary hyperparathyroidism), then a parathyroidectomy should be considered, although these patients are often too sick to undergo surgery. Good wound care to prevent infection and promote healing is important, though rarely effective, as tissue perfusion is often insufficient to permit good healing. Sometimes surgical debridement is effective, as it can remove the poorly perfused tissue. Effective pain control is extremely important, as the patient is typically in extreme pain from tissue ischemia. The prognosis is grim. The necrotic tissue typically takes an extremely long time to heal, if it ever heals. These necrotic areas provide an excellent portal for microbial entry as well, and patients often develop difficult-to-treat infections, which can be fatal. Miliaria Rubra Miliaria rubra is extremely common. It can happen in any patient who spends significant amounts of time in their hospital bed. Miliaria rubra presents as asymptomatic to slightly itchy papules on skin that spends significant amounts of time in contact with the bed. Miliaria rubra happens when sweat becomes trapped in the eccrine ducts. Chronic pressure on the skin by the bed prevents the sweat from progressing out of the ducts. As the sweat sits in the duct, an inflammatory response occurs and manifests as red papules. Miliaria does not require treatment. It can be a sign that a patient has limited mobility and is not moving around much. Limited mobility and infrequent position changes are also risk factors for decubitus ulcers, so miliaria rubra can be considered an indicator of risk for sacral decubitus ulcers, and steps should be taken to prevent sacral decubiti from developing (frequent position changes and possibly specialty pressure distribution beds). Once the skin is not being pressed against the bed all day, the condition starts to improve. It can take up to several weeks for the eruption to resolve once appropriate skin ventilation is achieved.