Warty Dyskeratoma Involving Two Adjoining Follicles

Graham and Helwig1 first described warty dyskeratoma (WD) as isolated Darier's disease in 1954 and this malady was more properly called warty dyskeratoma by Szymanski2 in 1957. WD is a rare tumor that is characterized by a solitary papule or nodule that is most commonly found on the scalp, face or neck. A cup-shaped invagination filled with a keratotic plug is the most histological common pattern. The invagination contains acantholytic dyskeratotic cells in the upper portion. In the lower portion of the invagination, there are numerous villi covered by a single layer of cells. The invagination has been interpreted as being a greatly dilated hair follicle. The changes almost always involve a single hair follicle. Tanay and Mehregan3 described that solitary lesion could exceptionally involve two to four close follicles. In Korea, only one case that revealed involvement of two adjoining follicles was reported by Chon et al.4.

We report here on an additional peculiar case of WD that involved two adjoining follicles.

A 47-year-old man visited our clinic with a 4 to 5-year history of a nodule on the scalp. The lesion was small and asymptomatic at first, but it had begun to increase in size and this was recently accompanied by tenderness. The patient pinched the lesion several times and he found that some whitish material was expressed through the pore. The patient was otherwise in good health.

The dermatologic examination revealed a 1.2×1.0 cm sized, erythematous, hairless nodule with a yellowish hyperkeratotic plug on the left parietal scalp (Fig. 1). On histologic examination, there were two large cup-shaped epidermal invaginations filled with keratinous material (Fig. 2A). The lower portion of each invagination showed suprabasal clefts and villi lined by a single layer of basaloid cells. There were typical corps ronds in the thickened granular layer and many acantholytic dyskeratotic cells above the villi. A moderate inflammatory infiltrate consisting of lymphocytes and histiocytes was observed in the dermis (Fig. 2B). On the basis of these clinical and histological findings, a diagnosis of WD was made. The lesion was completely removed by excisional biopsy. There were no signs of recurrence during the 7 month follow-up period.

Fig. 1
A solitary, well-defined, erythematous, hairless nodule with a hyperkeratotic plug on the left parietal scalp.

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Fig. 2
(A) Two large cup-shaped invaginations containing keratinous material (H&E, ×40). (B) The lower portion of each invagination shows suprabasal clefts and villi with acantholytic dyskeratotic cells. Typical corps ronds in the granular layer and a moderate inflammatory infiltrate consisting of lymphocytes and histiocytes in the dermis are observed (H&E, ×100).

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Isolated lesions with the histologic features of focal acantholytic dyskeratosis were first given special standing by Graham and Helwig1 as isolated dyskeratosis follicularis. Szymanski2 first introduced the name warty dyskeratoma in his review of seven new cases.

WD frequently arises as a single lesion with a central keratotic plug on the skin of the head or neck of middle-aged or older persons. Yet multiple lesions5, 6 and involvement of the oral7 and genital8 mucosa have occasionally been reported. The patient frequently states symptoms of pruritus and they may complain of recurrent foul-smelling cheesy drainage from the lesions. There may be central bleeding associated with trauma to the lesion.

Histologically, a cup-shaped invagination filled with a keratotic plug is observed. The lesion almost always involves a single hair follicle. Although it is very rare, adjoining follicles within a solitary lesion can be involved3, 4, 9. The invagination contains numerous acantholytic dyskeratotic cells and typical corps ronds can be seen at the entrance to the invagination.

In the lower portion of the invagination, there are many villi that are often covered by a single layer of basaloid cells and these villi protrude upward. In our case, two adjoining follicles were involved and each showed the typical histologic features of WD. Besides the most common cup-shaped type, Kaddu et al.10 reported two additional patterns of WD, that is, the cystic and nodular patterns. The cystic lesions have shown large, well-defined, cystic structures in the dermis, which were lined by epithelial cells and filled with masses of keratin material. The nodular lesions showed small, well circumscribed, solid aggregations of epithelial cells in the dermis. They were connected to the epidermis and the epidermis showed hyperplasia.

Focal acantholytic dyskeratosis is not a histologic hallmark of WD. It is also observed in Darier's disease or transient acantholytic dermatosis; some neoplasms such as acantholytic squamous cell carcinoma, actinic keratosis and basal cell carcinoma may present with similar histologic feature. In our case, the clinical appearance of WD was so distinctive that Darier's disease and transient acantholytic dermatosis could be easily excluded. The lack of cellular atypia and specific morphological features did not support the diagnosis of squamous cell carcinoma, actinic keratosis or basal cell carcinoma.

The etiology of WD is unclear, but a viral infection, smoking, autoimmunity, and ultraviolet light have been postulated to play a role. Szymanski2 showed the presence of viral DNA and RNA in the epithelial cells lining the villi and he proposed that viral infection was the cause of WD. But there has been no further evidence to support this hypothesis. The idea that chronic actinic damage was responsible for the development of WD was contradicted by its occurrence in areas unexposed to sunlight. Many authors3, 10, 11 have suggested a follicular origin for WD, but mucosal lesions that lack follicle could not be explained by their proposal. For this reason, some authors have insisted that oral WD may represent another entity rather than true WDs.

The treatment of choice of WD is surgical excision. Curettement with electro-desiccation and irradiation with X-ray had been tried, but these were followed by recurrence3. A case of successful treatment with tazarotenic acid gel12 has been reported. In our patient, there was no evidence of recurrence after excisional biopsy.

In conclusion, we describe here a peculiar case of WD that involved two adjoining hair follicles within a solitary lesion.