Warty dyskeratoma on the scalp mimicking keratoacanthoma

How to cite this article:
Lee JH, Uh JA, Kim JH, Lee SK, Kim MS, Lee UH. Warty dyskeratoma on the scalp mimicking keratoacanthoma. Indian J Pathol Microbiol 2023;66:659-60

Warty dyskeratoma and keratoacanthoma (KA) are skin tumors with nodules and a keratotic plug in the center. Warty dyskeratoma is a benign tumor that occurs mainly in the head and neck of adults,[1] whereas KA is a variant of a well-differentiated squamous cell carcinoma (SCC) that grows rapidly and may regress spontaneously. In some cases, KA may evolve into invasive SCC or metastasize and, therefore, should be carefully monitored.[2] We report a case of Warty dyskeratoma of the scalp mimicking KA, which clinically manifested as a nodule with a central keratotic plug and developed rapidly.

A 92-year-old man presented with an itchy solitary, firm, reddish nodule with a central keratotic plug on the occipital scalp [Figure 1]a. The lesion occurred 6 months previously, and its size rapidly increased within months. The patient had been prescribed medication for benign prostatic hyperplasia. The biopsy specimen showed cup-shaped, keratin-filled invagination of the epidermis with suprabasal clefting. Acantholytic and dyskeratotic cells were present beneath the invagination, but atypical cells or glassy, pale, squamous proliferating epithelial cells were not observed [Figure 1]b and [Figure 1]c. The patient was diagnosed with Warty dyskeratoma, and there was no evidence of recurrence for 6 months after its removal.

Figure 1: Clinical and histological picture of the case. (a) Solitary, 4-mm sized firm reddish nodule with a central keratotic plug on the occipital scalp. (b) Cup-shaped keratin-filled invagination with hyperkeratosis, acanthosis, and a marked suprabasal acantholytic cleft in the epidermis (hematoxylin and eosin [H and E], magnification ×40). (c) Numerous projecting villi lining a single layer of basal cells and acantholytic and dyskeratotic cells (H and E, magnification × 200)

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Warty dyskeratoma, a benign epidermoid tumor, clinically manifests on the head and neck of adults in the form of a papule or nodule with umbilical central invagination.[3] Histologically, it is characterized by a cup-shaped epidermal invagination containing keratinous material and acantholysis of epidermal keratinocytes and may be accompanied by pilosebaceous involvement. According to Kaddu et al.,[4] Warty dyskeratoma is classified into three types according to the architectural patterns: cup-shaped, cystic, and nodular; the present case can be classified as the cup-shaped type. As Warty dyskeratoma is a benign tumor, removal by simple resection is the treatment of choice.[1]

Owing to the presence of a keratotic plug in the central invagination, Warty dyskeratoma may appear clinically similar to KA, requiring a differential diagnosis [Table 1]. KA occurs mainly in the sun-exposed areas in middle-aged men. Furthermore, nodules of KA tend to be larger than those of Warty dyskeratoma, starting as a small papule, growing rapidly for months, and then regressing. Histologically, unlike Warty dyskeratoma, KA shows the absence of acantholytic cells, but shows cellular atypia and glassy, large keratinocytes. Although it is controversial whether KA is benign or malignant, it is considered to be a subtype of a well-differentiated SCC, and full-thickness fusiform excision is recommended owing to its ability to metastasize and become invasive, although rarely. No specific margin for excision of KA has been recommended, but 5 mm is advised, as in noninvasive SCC.[2,5]

Table 1: Clinical and histological differences between Warty dyskeratoma and keratoacanthoma

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Thus, we report a case of Warty dyskeratoma mimicking KA, considered as a type of SCC.

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The authors certify that they have obtained all appropriate patient consent forms. In the form the patient (s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Acknowledgements

This research received no specific grant from any funding agency in the public commercial or-not-for profit sectors.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

References

1.Kang S, Amagai M, Bruckner AL, Enk AH, Margolis DJ, McMichael AJ, et al. Fitzpatrick's Dermatology. 9th ed. New York: McGraw Hill Education; 2019. p. 1806.

2.Kwiek B, Schwartz RA. Keratoacanthoma (KA): An update and review. J Am Acad Dermatol 2016;74:1220-33.

3.Jang EJ, Lee JY, Kim MK, Yoon TY. Warty dyskeratoma involving two adjoining follicles. Ann Dermatol 2011;23:98-100.

4.Kaddu S, Dong H, Mayer G, Kerl H, Cerroni L. Warty dyskeratoma--”follicular dyskeratoma”: Analysis of clinicopathologic features of a distinctive follicular adnexal neoplasm. J Am Acad Dermatol 2002;47:423-8.