This month’s news from across the specialty
What’s hot
January 1, 2025
In this monthly column, members of the DermWorld Editorial Advisory Workgroup identify exciting news from across the specialty.
As dermatologists, we often advise our patients to keep their post-operative dressings dry and in place for 24-27 hours to reduce infection risk, prevent bleeding, and reduce outside disturbances to the healing wound. However, these restrictions have little supporting evidence and disrupt our patients’ daily activities such as bathing and exercise. A recent JAAD study compared standard wound management of keeping post-operative wounds dry and covered (48 hours) with early (six hours) postoperative water exposure. A total of 437 patients were randomized to either the early water exposure (shower, tub bath, pool) or standard cohort. Patients underwent excision for both benign and malignant lesions by both standard excision and Mohs surgery with immediate reconstruction. Non-standard procedures/patients were excluded from the study (i.e., staged reconstructions, second intent healing, grafts, patients requiring antibiotics). Patients were blindly evaluated postoperatively on days seven and 14 and at six months.
The authors found no statistical difference between rates of culture-proven infection, bleeding, bruising, or scar cosmesis between the two groups. The authors concluded that wounds can get wet during the immediate postoperative period and patients should be allowed to continue their normal personal hygiene practices.
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Patients with pemphigus may present a diagnostic challenge for dermatologists. In general, if a routine biopsy raises the possibility of pemphigus, it is recommended that supplemental testing be performed, including direct immunofluorescence, indirect immunofluorescence, or ELISA testing for DSG1 and DSG3. A recent study evaluated the use of C3d immunohistochemical staining on formalin-fixed paraffin embedded tissue (routine biopsy) for the diagnosis of pemphigus (Arch Pathol Lab Med. 2024 148:1022–7). There are a few prior studies in the literature reporting the benefit of C3d staining to aid in the diagnosis of bullous pemphigoid. Utilizing routine formalin-fixed tissue, the authors studied 63 pemphigus patients and 52 controls. Biopsies were stained for C3d yielding a sensitivity of 71% and a specificity of 96.4%. These results were similar to those using direct immunofluorescence on the fresh tissue. The authors also noted that this method was more sensitive for pemphigus vulgaris than for pemphigus foliaceus. Rare false positive cases were noted. This stain provides another diagnostic option especially if there are barriers to completing the supplemental testing.
A patient was started on phenytoin. Four weeks later, she developed a diffuse morbilliform eruption with facial erythema, edema, and pustules. She also had fever, lymphadenopathy, transaminitis, and atypical lymphocytes. The dermatology consult team performed a 4-mm punch biopsy of a clinically non-pustular area on her trunk. The histopathology result was acute generalized exanthematous pustulosis (AGEP). Since this was an unusual latency period for AGEP, the resident went to the literature to look for other cases of late-onset AGEP and was able to find cases due to hydroxychloroquine. The patient was then presented at a teaching conference as the first case of phenytoin-induced AGEP in the world. What is the lesson here? Think of horses before thinking of zebras. Phenytoin does not cause AGEP. Phenytoin is a prototype drug for drug-induced hypersensitivity syndrome (DIHS). The skin manifestations of DIHS are polymorphic, so a skin biopsy may not be helpful and may steer one to the wrong diagnosis, as in this case. Pustules can also be seen in DIHS. The diagnosis of DIHS is based on a constellation of findings — the culprit drug, the latency period, fever, lymphadenopathy, and transaminitis. A skin biopsy is not required to fulfill the diagnostic criteria for DIHS (J Am Acad Derm. 2024; 90(5): 885-908).
More What’s Hot!
Check out more What’s Hot columns from the DermWorld Editorial Advisory Workgroup.
Shingrix, the recombinant zoster (shingles) vaccine, is remarkably effective at preventing zoster and postherpetic neuralgia (PHN). Might Shingrix’s benefits extend beyond zoster and PHN? As reported in a JAMA article, Shingrix might also prevent or delay dementia and dementia-associated mortality.
The hypothesis that infections might trigger dementia is gaining traction, especially as treatments targeting amyloid-B protein in the brain, the putative cause of Alzheimer’s dementia, have effectively cleared that protein while failing to treat dementia. Researchers have theorized that Shingrix (and other vaccines) might work against dementia by preventing infections, which increase brain inflammation that leads to dementia.
Numerous observational studies have investigated whether Shingrix might protect against dementia. These studies have tried to adjust for “healthy vaccine bias,” the phenomenon that healthier people are more likely to get vaccines and less likely, because they are healthy, to develop dementia. Studies have also explored whether the live zoster vaccine (Zostavax, no longer available in the U.S.) might also protect against dementia — and if so, how its mechanism and effectiveness compare with Shingrix.
Data regarding Shingrix’s effectiveness as a vaccine against dementia are suggestive of a benefit, although the evidence is not overwhelming. Even if it is effective, it’s not a silver bullet. Unfortunately, Shingrix uptake in the U.S. is suboptimal, with less than one-third of eligible people having been vaccinated. They’ll be losing out on protection from zoster and PHN — and potentially more.
