An 11-year-old girl presented with a lesion that had been growing for a month on a congenital pre-existing scalp lesion. Dermatological examination revealed a 3cm yellowish alopecic patch with a verrucous surface on the temporal area, surmounted in its lower extremity by a 1cm erythematous growth (Fig. 1). Dermoscopy showed yellowish globules and a brownish background for the yellowish patch (Fig. 2a), while the excrescence displayed hemorrhagic suffusions, an erythematous background, and polymorphic vascularization (Fig. 2b).

	Figure 1: Erythematous growth resting on a yellowish alopecic plaque.
	Figure 2: (a) Eythematous background, hemorrhagic suffusions and polymorphous vessels (b) Yellowish globules and brown background.

An excisional biopsy revealed a hyperplastic, verrucous epidermis topped by ortho- and parakeratotic keratosis. The dermis was the site of papillary glandular proliferation in connection with the epidermis. It was bordered by a double layer of apocrine epithelial and myoepithelial cells. There was an associated lymphoplasmacytic inflammatory infiltrate, concluding to a syringocystadenoma papilliferum.

Nevus sebaceus of Jadassohn (NSJ) is a congenital dysembryoplasia involving the pilosebaceous follicle, epidermis and other adnexal structures. Clinically, it presents as a yellowish alopecic patch in childhood, which becomes verrucous and raises at puberty. NSJ is characterized by a risk of transformation into malignant tumors such as basal cell carcinoma or the development of secondary benign adnexal tumors. This usually occurs after the age of 40 years [1]. However, our patient developed a papilliferum syringocystadenoma at an early age. It is a benign apocrine sweat tumor, and one of the most common tumors to arise in the NSJ [2]. It’s characterized histologically by the presence of papillary processes lined with two layers of epithelial cells. [3].

In view of the progressive nature of the NSJ, some authors propose excision with a histological study around puberty, while others take a more conservative approach, proposing excision only if there are clinical signs of malignant transformation of the NSJ.

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