Hypopigmented pityriasis versicolor developing on a pre-existing Becker's Naevus
M C Baruah
Department of Dermatology & STD, University College of Medical Sciences & Guru Teg Bahadur Hospital, Shohdara, Delhi-110 095
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Bhogal C S, Singal A, Baruah M C. Hypopigmented pityriasis versicolor developing on a pre-existing Becker's Naevus . Indian J Dermatol Venereol Leprol 2002;68:43-44
AbstractA 24-year-old male presenting with pityriasis versicolor developing on a pre-existing lesion of Becker's naevus is being reported for its rare occurrence.
Becker′s melanosis associated with hypopigmented pityriasis versicolor was first described by Wright in 1979 and then by Signal in 1998. We report yet another case of hypopigmented pityriasis versicolor developing on a pre-existing Becker′s naevus in a young male.
A 24-year-old man presented to Dermatology out-patient department with an asymptomatic, irregular, dark-brown hyperpigmented lesion of about 10x10 cm size of 6 years duration, overlying right anterior chest wall and extending onto the right shoulder. The lesion had increased hair growth on one of the margins. Patient noticed asymptomatic multiple, discrete, hypopigmented, mildly scaly lesions developing on the pigmented lesion during last 2 months. A clinical diagnosis of pityriasis versicolor overlying Becker′s naevus was made. [Figure - 1]
Patient did not reveal any other local, systemic or structural abnormalities like deformity of the long bones.
10% KOH smear from hypopigmented lesions demonstrated plenty of filamentous hyphae and spores confirming the clinical diagnosis of pityriasis versicolor. Skin biopsy from the hyperpigmented lesion was consistent with Becker′s naevus.
Patient was advised topical 1% clotrimazole cream twice daily for 2 weeks, following which his scraping for fungus became negative but hypopigmented lesions took about 4 more weeks (post-treatment) to disappear completely.
A number of cases of Becker′s melanosis have been discribed in world leterature since its original description in 1949. Lesions are usually single and unilateral but may be multiple and are usually located on shoulder, and/or chesst. They have also been described on forehead, eyelids, cheeks, neck, abdomen, hip and lower legs. A plethora of associations like structural anomalies, smooth muscle hamartomasand malignant melanomas have also been described.
Unbanek and Johnson in 1978 suggested the occurrence of functional alternation of pilo-sebaceous apparatus in Becker′s naevus. Mehregan also indicated enlargement of sebaceous glandular tissue in Becker′s naevus. Both these observations to an extent, explain the preferential localization of pityriasis versicolor lesions confined to Becker′s naevus caused by lipophilic dimorphic fungus, Pityrosporum orbiculare in our patient.
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