The nevus sebaceous of Jadassohn usually affects the face or scalp. It tends to evolve in three stages, and the final stage is characterized by the appearance of tumours. We present the case of a facial nevus sebaceous of Jadasshon in which a basal cell carcinoma developed. We also explore the diagnosis of this disease, which was established through dermoscopy, and propose using this technique in the clinical follow-up of this type of hamartoma, thereby allowing the early detection of cancer development.

EditorCongenital eccrine naevus is a rare clinical entity. Fewer than 20 cases had been reported, and only three cases were congenital. 1,2 We present a child with congenital localized hyperhidrosis on the forearm. To the best of our knowledge, this is the first congenital eccrine naevus successfully treated with botulinum toxin type A.A 12-year-old girl with no significant past medical history presented with a history of localized excessive sweating on the right forearm from birth. The episodes were twice a week and were initially confused by their parents with enuresis. At 6 years of age, the episodes began more frequently, compromising her school activities. The episodes occurred daily, were preceded by a paresthesic sensation on the area and were precipitated by heat, physical activity and specially by the muscular strain of handwriting. Physical and neurological examinations were normal. Epidermic changes were not observed in the hyperhidrotic area.A provocation test with exposition to heat for 30 min confirmed a hyperhidrotic area of 5 × 4 cm localized on the ulnar emminence of the right wrist. Sweat dripped from the area ( fig. 1). An incisional biopsy specimen showed a proliferation of eccrine glands of the deep dermis and hypodermis ( fig. 2).Topical treatment with aluminium chloride 20% was unsuccessful. Surgical extirpation was discarded due to the size of the lesion. Considering the interference with her school activities and according to her mother's previous consent, treatment with botulinum toxin type A (Botox Allergan, USA) was performed. Botulinum toxin type A was diluted in 4 mL of saline solution 0.9%, with 5 U per intradermic injection, at intervals of 0.5 to 1 cm.

Argyria is a rare disease caused by prolonged skin contact with silver. Localized cases have been described regarding the use of topical medications, and trauma with objects containing this metal such as acupuncture needles and jewelry. Clinically, a macule or a patch, round or oval, appears in the infected area, with a characteristic bluey-gray color. To our knowledge this is the first time that this clinical condition has been described through the use of dermoscopy.

Targetoid hemosiderotic hemangioma (THH) or hobnail hemangioma (HH) is a benign vascular lesion that presents with the classical clinical presentation of a ring-shaped tumor having a targetoid appearance, with a central purple-brown papule surrounded by a thin pale area and an ecchymotic ring on the outside. Dermoscopic features and patterns of HH have been documented and have proven to be sufficient to establish a clinical diagnosis in many cases. We present a facial lesion in which both the clinical presentation and dermoscopy were atypical. The presence of arborizing vessels in the dermoscopic pattern, never before described for this lesion, led us to the diagnosis of basocellular carcinoma (BCC). We also report the changes in this pattern experienced over 12 months of progression and their correlation with the histopathologic findings.

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