in all cases, indicating the difficulty in identifying these lesions clinically. In fact, there was a report of a 12-year-old with ectopic sebaceous glands on the penis, which were clinically similar to ours, but histologically, the lesions demonstrated epidermal hyperplasia rather than sebaceous gland hyperplasia. 6 Clinically, SH of the penile shaft should be differentiated from pearly penile papules, molluscum contagiosum, Bowenoid papulosis, genital warts and lichen nitidus. Pearly penile papules are arranged in rows and are usually localized at the coronal edge. In our case, the papules were irregularly distributed and not confined to the coronal edge. Bowenoid papulosis and genital warts are multiform in size and shape and grow substantially with time, whereas in our case, the papules were uniform and showed minimal change over time. The individual lesions in lichen nitidus are white, glistening and flat, which is distinct from the yellowish, dome-shaped papules of SH.Histologically, the differential diagnoses include ectopic sebaceous glands, naevus sebaceous, sebaceous adenoma and sebaceous epithelioma. Although there is no universally accepted definition of SH, Wick et al . 1 defined SH by the presence of ≥ 4 sebaceous lobules attached to an infundibulum of a pilosebaceous unit. The cells comprising the lobules are fully mature with a thin rim of basaloid cells present at the periphery. It must be distinguished from ectopic sebaceous glands, where a group of small, mature sebaceous lobules are situated around a small sebaceous duct without an attached follicle. Naevus sebaceous differs from SH by the presence of hamartomatous pilosebaceous units, papillomatous epidermal hyperplasia and frequent apocrine elements. Sebaceous adenoma and sebaceous epithelioma commonly show multilayers of undifferentiated basaloid cells in the periphery. 1 In conclusion, our case suggests that SH should be considered in the differential diagnosis of a patient with tiny papular lesions on the penis. It is important to reassure the patient that this condition is not infectious. There is no need to pursue treatment other than for cosmetic reasons.
References1 Wick MR, Swanson PE, Barnhill RL. Sebaceous and pilar tumors. In: Crowson AN, Barnhill RL, eds. Textbook of Dermatopathology , 2nd edn. The McGraw-Hill, New York, 2004: 709-715. 2 Hyman AB, Brownstein MH. Tyson's 'glands'. Ectopic sebaceous glands and papillomatosis penis. Arch Dermatol 1969; 99 : 31-36. 3 Vergara G, Belinchón I, Sivestre JF, Albares MP, Pascual JC. Linear sebaceous gland hyperplasia of the penis: a case report. J Am Acad Dermatol 2003; 48 : 149-150. 4 Kumar A, Kossard S. Band-like sebaceous hyperplasia over the penis. Australas J Dermatol 1999; 40 : 47-48. 5 Carson HJ, Massa M, Reddy V. Sebaceous gland hyperplasia of the penis.