Diagnosis: Fox-Fordyce disease
Our patient had Fox-Fordyce disease, otherwise known as apocrine miliaria. A chronic, recurrent, inflammatory disease affecting the sweat glands, Fox-Fordyce disease is characterized by the presence of pruritic follicular papules limited strictly to areas of the body with apocrine glands. This uncommon disorder has a predilection for women, with a female-to-male ratio of 9:1. Onset usually occurs between the ages of 13 and 35 years. Only rarely has Fox-Fordyce been reported before puberty, in postmenopausal women, or in men.
Typically Fox-Fordyce disease presents as skin-colored papules measuring 1-3 mm on a slightly erythematous base. The lesions occur in follicular (or less commonly perifollicular) locations bearing apocrine glands. Besides the axillae, Fox-Fordyce disease can be seen in the mammary areolae, perineum, labia majora, and umbilicus. The lesions are pruritic; hairs tend to be sparse in the affected areas, possibly due to the patient’s rubbing and scratching. The pruritus can be triggered by emotional, pharmacologic, or physical factors that result in stimulation of apocrine secretion. Absence of apocrine secretion from the affected glands is common and attributed to obstruction of the apocrine duct at its entrance into the follicular wall. When the disease affects a large proportion of the apocrine glands, apocrine odor is reduced.
The exact etiology of Fox-Fordyce disease remains unclear, and no connection with genetic factors, metabolic abnormalities, or endocrine diseases has been established. Symptoms seem to improve in pregnant women. This beneficial effect of pregnancy is particularly evident during the last trimester.
Diagnosis of Fox-Fordyce disease is based on the presence of typical clinical findings and confirmed on biopsy. The characteristic histopathologic finding is vesicle formation in the intraepidermal portion of the apocrine duct. The peripheral portion of the duct is plugged by keratin, and dilation and rupture of the duct below this obstruction is seen. In time, secondary changes, such as spongiosis and acanthosis of the epidermis in the periductal area, along with inflammation of the dermis can be detected.
Although the typical clinical features of this disease limit the differential diagnosis, lichen simplex, lichen planus, and syringoma may be considered.
The treatment of Fox-Fordyce disease is frequently unsatisfactory. Several therapeutic approaches have been used, such as estrogens, topical and systemic corticosteroids, steroid injections, symptomatic topical treatment, topical tretinoin cream, and surgical excision. In our patient’s case, topical tretinoin relieved the pruritus.