Development is normal. Note brown papule not present in infancy. D, B and B, respectively. Nevus sebaceous of Jadassohn is a hamartoma of normal elements of the skin with a preponderance of sebaceous glands. It is a well circumscribed hairless plaque that is usually solitary.
Lesions are sporadic and occur in equal frequency in males and females in all races.
Typical lesions are round, oval or linear, measuring from 5 mm to several centimeters in diameter, although much larger lesions can occur. The most common location for nevus sebaceous is on the scalp and face. Typical lesions of nevus sebaceous are faintly notable to erythematous inflammed papules and plaques with alopecia present at birth or noted early in life. Lesions are responsive to maternal hormone stimulation accounting for the inflammation which usually resolves over several months. Many parents do not seek medical attention for this birthmark because the improvement noted early in life suggests that the birthmark will spontaneously involute.