Multiple white papules on the retroauricular fold

A 46-year-old man presented with a 1-year history of multiple white papules and a plaque affecting the right retroauricular fold. The papules gradually increased and were asymptomatic. There were no prior skin lesions or injury. There was no significant medical or family history. Physical examination found numerous, whitish-yellow papules 1 to 3 mm in diameter on a well-defined, oval, erythematous-edematous plaque on the right retroauricular fold (Fig 1). Dermoscopy manifestations of the lesions are shown in Fig 2. Results of a biopsy are shown in Fig 3.

Fig 1.

Fig 2.

Fig 3.

Question 1: What is the most likely diagnosis?

• A.Nevus comedonicus
• B.Milia en plaque (MEP)
• C.Syringoma
• D.Sebaceous hyperplasia
• E.Follicular mucinosis

Answers:

• A.Nevus comedonicus – Incorrect. Nevus comedonicus usually develops from birth to age 15 with comedo-like lesions. However, the age of onset in our patient is too old.
• B.MEP – Correct. MEP is a rare primary milia characterized by an erythematous plaque containing numerous milia. The region commonly involved is the retroauricular area.¹ Biopsy of this patient shows a keratin-filled cyst in the dermis (Fig 3).
• C.Syringoma – Incorrect. Syringomas are a neoplasms demonstrating sweat duct differentiation. Histologically, syringomas are characterized by dilated cystic spaces lined by 2 layers of cuboidal cells and epithelial strands of similar cells. Some of the cysts have small comma-like tails, which produce a distinctive picture, resembling tadpoles or the pattern of a paisley tie.
• D.Sebaceous hyperplasia – Incorrect. The lesions of sebaceous hyperplasia are small, cream colored or yellowish, umbilicated papules, 2 to 6 mm in diameter. Dermoscopy can be helpful in confirming the diagnosis and identifies the central crater, the yellow lobules, and the associated telangiectasia. Histologically, sebaceous hyperplasia demonstrates hyperplasia of 1 sebaceous gland, with the surrounding glands being of normal size.
• E.Follicular mucinosis – Incorrect. Follicular mucinosis can present as an acneiform eruption. Histologically, follicular mucinosis demonstrates large collections of mucin within the sebaceous gland and outer root sheath.

Question 2: Which of the following is the most characteristic dermoscopy manifestations of MEP?

• A.Multiple milia cysts
• B.Lacunae
• C.Polylobular whitish structureless areas
• D.Rosette sign
• E.Cerebriform pattern

Answers:

• A.Multiple milia cysts – Correct. In our patient, dermoscopy showed multiple milia cysts, comedo-like openings (follicular keratotic plugs) with branching vessels around (telangiectasia) (Fig 2).
• B.Lacunae – Incorrect. Lacunae are defined as multiple, clustered, well-demarcated, red to maroon to blue blobs with a round to oval shape. They are common in angiomas and angiokeratomas, not in MEP.
• C.Polylobular whitish structureless areas – Incorrect. In molluscum contagiosum, dermoscopy shows polylobular whitish structureless areas in the center surrounded by elongated blurred telangiectasia.
• D.Rosette sign – Incorrect. The rosette sign consists of a white 4-leaf clover–shaped structure. It can be seen in actinic damaged skin and in tumors such as basal cell carcinoma, melanoma, and thin squamous cell carcinoma.
• E.Cerebriform pattern – Incorrect. Cerebriform pattern is created by pigmented fissures and light ridges. This feature is common in seborrheic keratosis, not in MEP.

Question 3: Which of the following is the most common treatment of MEP?

• A.Manual extraction
• B.Topical glucocorticoid
• C.Photodynamic therapy
• D.Surgical excision
• E.Spontaneous regression

Answers:

• A.Manual extraction – Correct. Although there are many treatment options such as topical tretinoin and oral minocycline for MEP,2, 3 manual extraction is the most common treatment.
• B.Topical glucocorticoid – Incorrect. So far, there has been no report that MEP is successfully treated with topical glucocorticoid.
• C.Photodynamic therapy – Incorrect. Although some reports have shown that MEP is successfully treated by photodynamic therapy, photodynamic therapy is still not the first choice in MEP.
• D.Surgical excision – Incorrect. Surgical treatment is still one choice in some cases with failed therapy with medicines.
• E.Spontaneous regression – Incorrect. Although MEP is a benign condition, it mainly represents a cosmetic concern. Rarely, spontaneous regression may occur.⁴