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Pyoderma gangrenosum is a rare, neutrophil-mediated, auto-inflammatory dermatosis that wound care specialists must be prepared to recognise. This condition has clinical features analogous to infectious processes. There is no specific diagnostic test and the diagnosis is usually obtained from exclusion. Its early recognition and proper management with prompt initiation of immunosuppressive therapy are essential to improve the quality of life and the prognosis of patients., (© 2020 Medicalhelplines.com Inc (3M) and John Wiley & Sons Ltd.)

Myopericytoma is a soft-tissue tumor of perivascular cells (pericytes). It is slow-growing, usually asymptomatic, and generally benign, although a malignant variant has been described. The etiology is unknown, but it has been associated with local trauma. The most common location is on the distal extremities. Histologically, it is characterized by a well-circumscribed, non-encapsulated proliferation of spindle shaped cells similar to myofibroblasts with oval nuclei and eosinophilic cytoplasm, arranged in perivascular concentric rings. There are few mitoses and no necrosis is reported. The immunohistochemical analysis is positive for smooth muscle actin and negative or weakly positive for desmin. A low Ki-67 proliferation index is typical. Treatment is surgical excision with free margins. Recurrences after adequate excision are uncommon. We describe a 48-year-old woman with a myopericytoma in an unusual location (next to the inner corner of her left eye) who was treated with surgical excision; there has been no recurrence after 5 years of follow up.

Background: There is a major controversy over the natural behavior of keratoacanthoma (KA). KAs have been described as benign lesions, but also as variants of squamous cell carcinoma (SCC). Microscopic differentiation between these 2 entities is problematic, and sometimes impossible. Syndecan-1 (CD138) is an adhesion molecule whose expression appears to be inversely correlated with tumor invasiveness. Elevated Ki-67 expression is indicative of a high proliferation index, a feature of malignant tumors., Methods: Syndecan-1 and Ki-67 expression were assessed in 22 KA skin samples and in 17 SCC skin biopsies., Results: Syndecan-1 expression was diminished in the SCC specimens compared with the KA specimens ( P =.000). Ki-67 expression was increased in the SCC specimens compared with the KA specimens, with mean values of 9 and 0.08, respectively ( P =.000)., Limitations: Further studies that compare intermediate risk KAs to typical KAs and SCCs are required to corroborate these findings., Conclusion: The assessment of syndecan-1 and Ki-67 expression in skin biopsies is a helpful tool for differentiating KA and SCC

Objective: Longitudinal melanonychia (LM) is a common dermatologic problem encountered in everyday practice. Its diagnostic approach is critical as it can be an early sign of nail melanoma. Racial melanonychia is the entity most frequently associated with LM. Because there are no clinical data regarding these associations in a Mexican population, we conducted a prospective study., Methods: A total of 68 consecutive patients given the clinical diagnosis of LM were included and a nail biopsy was performed to determine its cause., Results: Racial melanonychia was found in 48 cases (68%), 4 cases (5.7%) were associated with benign melanocytic hyperplasia, and 4 cases (5.7%) had a nail apparatus malignancy., Limitations: Dermatoscopy and immunohistochemical stains were not used. Incisional transverse nail matrix biopsies were performed when melanonychia affected the middle portion of the nail plate., Conclusion: LM is most commonly associated with racial melanonychia in the Mexican population, but in nearly 6% of cases it may be linked with nail apparatus malignancy. To our knowledge, this is the first time a study of this nature was performed in a mestizo Hispanic population.

Background: The frequency of nail unit tumors is not well known because they are often misdiagnosed, and the clinical appearance of benign and malignant tumors is not characteristic., Patients and Methods: A total of 234 patients from the dermatology department of a general hospital in Mexico City were included in this study, from January 1982 to November 2006., Results: The tumors most frequently diagnosed were fibrous tumors (29.05%), osteocartilaginous tumors (21.79%), and myxoid pseudocysts (11.96%). Malignant melanoma occupied the fourth place (9.82%), and the second most frequent malignant tumor was squamous cell carcinoma (SCC; 4.70%). Among other tumors were glomus, neurofibromas, giant cell tumors of tendon sheath, and pyogenic granulomas. The nail plate was affected in 46.5% of the cases studied., Conclusion: This study in a Mexican population sheds light on the frequency and the alterations produced by nail unit tumors, which we must keep in mind for a more accurate diagnosis.