Who knows the cause of the plaque on a boy's nose?

Diagnosis: Alopecia mucinosa

Alopecia mucinosa was first described in 1957 by Hermann Pinkus, MD, in a case series of six patients.¹ His clinical description included slowly enlarging, well-defined plaques with alopecia that were usually confined to the scalp, face, or neck, or a combination of these areas.¹ Alopecia mucinosa* can also present as folliculocentric or comedone-like papules that coalesce into plaques. Rarely, plaques disseminate on the trunk and extremities.

Histopathologic features

Alopecia mucinosa is characterized histologically by follicular mucinosis, with mucin in the infundibulum, the follicle below it, and connected sebaceous lobules.^2,3 Epithelial mucinosis can also be found. In Pinkus's original description, he noted edema and mucin in the outer root sheath and sebaceous glands, with varying degrees of inflammation and follicular degeneration.

Onset and course

Alopecia mucinosa appears to have a bimodal age of onset, peaking in childhood and again in middle age. In the childhood variant, lesions develop over weeks to months. Plaques are typically solitary and occur on the scalp or face. Lesions often resolve without treatment.

In adults, plaques tend to follow a chronic course and generalize, with predominance on the face and trunk.

Spontaneous regression does not occur in adult alopecia mucinosa, and the eruption may progress to mycosis fungoides, a primary cutaneous T cell lymphoma.⁴ Although such progression does not usually occur in affected children, some investigators emphasize that alopecia mucinosa has the potential to evolve to lymphoma at any age, even when atypical lymphocytes or clonality of T cells, or both, are absent.⁵ Long-term monitoring for development of lymphoma is therefore recommended for all patients.^6-8

Management

Treatment of alopecia mucinosa is unnecessary in a child, although biopsy is required to establish the diagnosis and cosmetically disfiguring lesions may melt away with application of a topical or intralesional corticosteroid.

REFERENCES

1. Pinkus H: Alopecia mucinosa; inflammatory plaques with alopecia characterized by root-sheath mucinosis. AMA Arch Dermatol 1957;76:419

2. Gibson L, Muller, SA, Leiferman KM, et al: Follicular mucinosis: Clinical and histopathologic study. J Am Acad Dermatol 1989;66;387

3. Mehregan D, Gibson LE, Muller SA: Follicular mucinosis: Histopathologic review of 33 cases. Mayo Clin Proc 1991;66:387

4. Rebora A, Rongioletti F: Alopecia mucinosa, in Bolognia JL, Jorizzo JL, Rapini RP (eds): Dermatology. London, Elsevier Science, 2003, pp656,657

5. Boer A, Guo Y, Ackerman AB: Alopecia mucinosis in mycosis fngoides. Am J Dermatopathol 2004;26:33

6. Brown H, Gibson LE, Pujol RM, et al: Primary follicular mucinosis: Long-term follow-up of patients younger than 40 years with and without clonal T-cell receptor gene rearrangement. J Am Acad Dermatol 2002;47:856