Warty dyskeratoma (WD) is a benign endophytic cutaneous lesion, characterized by proliferation of squamous epithelium, acantholysis, and dyskeratosis (Weedon et al. 2005). Based on its regular association with pilosebaceous units, it has been suggested that WD is a true benign follicular adnexal neoplasm (Kaddu et al. 2002). WD is rare and has a predilection for the face, scalp, and neck. It presents as a papule, nodule, or cyst with a central keratotic plug, grows slowly till it reaches 1–2 cm in diameter, and persists indefinitely. Acantholysis and dyskeratosis are the characteristic microscopic features.
Clinicopathological correlation in conditions characterized by acantholytic dyskeratosis
| Diagnosis | Warty dyskeratoma | Darier disease | Acantholytic dyskeratotic acanthoma | Acantholytic dyskeratotic epidermal nevus | Focal acantholytic dyskeratosis | Squamous cell carcinoma acantholytic type |
|---|---|---|---|---|---|---|
| Clinical features | Solitary papule or nodule | Multiple warty papules over serborrheic areas, cobblestonning of the palate, v shaped nicking of the nails, longitudinal erythronychia | Solitary papules on the trunk | Linear verrucous papules and plaques (linear verrucous epidermal nevus) | Incidental acantholytic dyskeratosis seen in specimens of benign and malignant neoplasms including Basal cell carcinoma, dermatofibroma, keratoacanthoma and psoriasis | Verrucous, hyperkeratotic papule, plaque or nodule. |
| Histopathological findings | Cup shaped invagination, acantholytic dyskeratotic cells in follicular infundibular epithelium | Acantholytic dyskeratosis, corps ronds, grains in a case classical clinical presentation | Acantholytic dyskeratosis, hyperkeratosis, lack of cup shaped invagination | Acantholytic dyskeratosis within epidermal nevi | Incidental finding noted only in focal areas of benign and malignant neoplasms | Acantholytic cells, dyskeratosis, atypia, mitotic figures, absence of cyst-like configuration as seen in warty dyskeratoma |
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.
