Histologic Hitchhikers: A Review of Common Exogenous Artifacts Encountered During Mohs Micrographic Surgery.

BACKGROUND: Exogenous artifacts can interfere with accurate histologic tissue evaluation on frozen sections during Mohs micrographic surgery (MMS). Mohs surgeons should be aware of these anomalies to avoid potential misdiagnoses. OBJECTIVE: To review exogenous artifacts encountered in frozen tissue pathology during MMS. METHODS: A literature search was conducted in PubMed to identify studies reporting on exogenous artifacts encountered during MMS and a list of previously described exogenous artifacts was compiled. A retrospective examination of frozen histology slides from recent Mohs cases at the authors' institution was performed to obtain illustrative examples of these artifacts, supplemented by formalin-fixed paraffin-embedded samples when frozen examples could not be found. RESULTS: Exogenous artifacts represent foreign bodies that have been externally introduced into the skin or artifacts resulting from other external factors. If frozen section evaluation is inaccurate, overdiagnosis can occur during MMS, resulting in unnecessary layers, larger margins, and more complex reconstructions. These exogenous tissue changes can mimic inflammatory processes and melanocytic or keratinocyte malignancies on histology. CONCLUSION: Exogenous artifacts are common findings during margin assessment in Mohs micrographic surgery. The resulting histological findings can be confusing but correlating them with the clinical and surgical history often reassures surgeons. Recognizing these artifacts facilitates accurate diagnosis and promotes optimal patient care.

Postoperative Infections in Dermatologic Surgery: The Role of Wound Cultures.

BACKGROUND: Dermatologic surgery is associated with low postoperative infection rates, averaging from approximately 1% to 4.25%. Often, postoperative infections are treated empirically based on clinical diagnosis of infection, given it can take 48 to 72 hours for a wound culture to identify a pathogen. OBJECTIVE: We aimed to evaluate the efficacy of empiric antibiotics in dermatologic surgery postoperative infections and if wound cultures change postoperative antibiotic therapy. METHODS: A 7-center, retrospective analysis of postoperative infections, with culture data, in dermatologic surgery patients was performed. RESULTS: Of 91 cases of clinically diagnosed postoperative infection, 82.4% (n = 75) were successfully treated with empiric oral antibiotics (95% confidence interval [0.73-0.89], p < .0001). In 16 (17.6%) cases, initial empiric antibiotics were unsuccessful, and wound culture results altered antibiotic therapy in 9 cases (9.9%) with 6 (6.6%) of these cases requiring additional coverage for methicillin-resistant Staphylococcus aureus (MRSA). CONCLUSION: Empiric antibiotic treatment is usually appropriate for patients with postoperative surgical-site infections with wound cultures altering antibiotic management in a minority of cases. When empiric antibiotics fail, lack of MRSA coverage is usually the cause; therefore, providers should be aware of local MRSA prevalence and susceptibilities.

Dermatoses associated with mites other than Sarcoptes.

Mites are arthropods of the subclass Acari (Acarina). Although Sarcoptes is the mite most commonly recognized as a cause of human skin disease in the United States, numerous other mite-associated dermatoses have been described, and merit familiarity on the part of physicians treating skin disease. This review discusses several non-scabies mites and their associated diseases, including Demodex, chiggers, Cheyletiella, bird mites, grain itch, oak leaf itch, grocer's itch, tropical rat mite, snake mite, and Psoroptes.