Ecthyma gangrenosum is a rare skin infection classically associated with Pseudomonas aeruginosa. We performed a retrospective study of all cases diagnosed with ecthyma gangrenosum from 2004-2010 in a university hospital in Mexico (8 cases, 5 female patients and 3 male patients, ages between 4 months and 2 years). The most common risk factor for ecthyma gangrenosum is neutropenia in immunocompromised patients. In previously healthy patients, immunological evaluation is important to rule out underlying immunodeficiency. Ecthyma gangrenosum in healthy patients has a high mortality rate and early diagnosis and aggressive antibiotic treatment is imperative as it can improve patients' prognosis.

Trichoscopy (dermoscopy of the hair and scalp) is a technique that improves diagnostic accuracy and follow-up with hair and scalp disorders. Although several studies of trichoscopy have been made in Caucasian and Asian populations, little has been published regarding trichoscopy findings in skin of color, despite the great prevalence of hair diseases in populations with this kind of skin. The aim of this review was to describe the trichoscopic features of normal scalp and of hair disorders in patients with dark skin phototypes. This will help dermatologists to distinguish between unique trichoscopic features of dark skin, and allow them to provide more accurate diagnoses and treatments for these patients.

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Onychomatricoma (OM) presenting as a longitudinal melanonychia is a very uncommon clinical presentation with very few cases in the literature. Our aim in this article is to report four cases of pigmented OM, and describe their clinical and dermoscopic findings and the importance of the differential diagnoses, especially with melanoma.

Angioimmunoblastic T-cell lymphoma (AITL) accounts for 15-20% of all peripheral T-cell lymphomas. It is a rare subtype of CD4 T-cell peripheral lymphoma that affects aged individuals, causing B symptoms, generalized lymphadenopathy and hepatosplenomegaly. Its pathogenesis is still unclear, but in some cases it has been associated with infection, allergic reaction or drug exposure. The majority of patients are diagnosed in an advanced stage and anthracycline based regimen is considered the first-line therapy. Skin involvement is not well characterized, occurring in up to 50% of patients and presenting as nonspecific rash, macules, papules, petechiae, purpura, nodules and urticaria. We present the illustrative case of a 55-year-old woman with an AITL who presented prominent skin findings, arthritis, lymphadenopathy and hypereosinophilia. Skin biopsy reported a T-cell lymphoma and the diagnosis of AITL was confirmed by an axillary lymph node biopsy, which was also positive for Epstein-Barr virus. Chemotherapy with CHOP-21 and thalidomide was given, accomplishing complete remission after six cycles.