|LETTER TO THE EDITOR
|Ahead of print publication
Basal cell carcinoma arising from an epidermoid cyst: A histopathological surprise
Geeti Khullar1, Deepti Agarwal2, Mithilesh Chandra2
1 Department of Dermatology and Sexually Transmitted Diseases, Vardhman Mahavir Medical College and Safdarjung Hospital, New Delhi, India
2 Pathology Consultancy Services, B-6, Sector 27, Noida, Uttar Pradesh, India
|Date of Submission||09-May-2020|
|Date of Decision||04-Jun-2020|
|Date of Acceptance||08-Jul-2020|
|Date of Web Publication||19-Sep-2020|
Department of Dermatology and Sexually Transmitted Diseases, Vardhman Mahavir Medical College and Safdarjung Hospital, New Delhi - 110 029
Source of Support: None, Conflict of Interest: None
|How to cite this URL:|
Khullar G, Agarwal D, Chandra M. Basal cell carcinoma arising from an epidermoid cyst: A histopathological surprise. Indian Dermatol Online J [Epub ahead of print] [cited 2020 Oct 29]. Available from: https://www.idoj.in/preprintarticle.asp?id=295452
Epidermoid or infundibular cysts are the most frequent type of cutaneous cysts. Though typically benign, malignant transformation in epidermoid cysts has been exceptionally reported.,,
A 42-year-old woman presented with an asymptomatic swelling on the right shoulder since 15 years. She noticed a gradual increase in the size of the lesion in the last one year. Cutaneous examination revealed a skin-colored to erythematous, firm, nontender nodule of size 2 × 2 cm on the right shoulder [Figure 1]. The nodule was completely excised and sent for histopathological examination with a provisional diagnosis of an epidermoid cyst. The resected specimen showed a cyst in the deep dermis, lined by a 4–5 cell thick layer of epidermal cells with thin granular layer and the lumen-containing proteinaceous fluid [Figure 2]a, [Figure 2]b, [Figure 2]c. The cyst lining showed a gradual increase in the thickness, with transformation into nests of basaloid cells showing peripheral palisading and peritumoral clefting. Many mitotic figures were also noted. Melanin pigment was present within the tumor cells and in the stroma [Figure 2]d and [Figure 2]e. There was no extension of the tumor into the subcutaneous fat. The resected margins were free of malignant cells. Based on the histopathological findings, a diagnosis of pigmented nodular basal cell carcinoma arising from the wall of an epidermoid cyst was made. There has been no recurrence of the cyst or tumor after 1.5 years of follow up.
|Figure 1: Skin-colored to erythematous nodule measuring 2 × 2 cm on the right shoulder|
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|Figure 2: (a) Cyst located in the deep dermis with nests of basaloid tumor cells arising from the lining of the cyst (hematoxylin-eosin, x40). (b) The cyst wall is lined by 4–5 layered thick stratified squamous epithelium and contains proteinaceous fluid in its lumen. Nests of basaloid cells are originating from the basal layer of the cyst wall. The stroma of the tumor contains clumps of melanin pigment (hematoxylin-eosin, x100). (c) Squamous epithelium, including a thin granular layer lining the wall of the epidermoid cyst (hematoxylin-eosin, x200). (d) Islands of basaloid tumor cells are infiltrating the cyst wall. The cells show hyperchromatic nuclei, scanty cytoplasm, peripheral palisading and are separated from the stroma by retraction spaces. Melanin pigment is noted within the tumor islands (hematoxylin-eosin, x200). (e) Higher magnification showing nests of basaloid cells with peripheral palisading (marked with arrow), mitotic figures, and retraction spaces (hematoxylin-eosin, x400)|
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Malignant tumors arising from the wall of the epidermoid cysts are rarely reported in English literature, with an incidence of about 1.1%. Majority of these (70%) have been described as squamous cell carcinomas (SCC) and only 10% as basal cell carcinomas (BCC). It is estimated that the rate of BCC developing in epidermoid cysts is roughly 0.1%. Cameronet al. reported the development of carcinoma in about 0.045% of all epidermoid cysts (total number = 2246), of which only one was SCC and there were no other carcinomas. In a study of 637 excised epidermoid cysts, BCC was observed in six cases and SCC in one case. All cases of BCC originated from cysts located on the exposed sites. In another study on tumors arising from cutaneous cysts, 51 comprised of SCC, 18 of BCC, three were basosquamous, and five were nonclassified. Out of the 18 cases of BCC, eight developed from the epidermoid cysts, three from the pilar cysts, and the remaining seven were associated with unspecified cysts.
The development of BCC from the lining of an epidermoid cyst may be explained by their common origin from the infundibular portion of the hair follicles. As BCC arising from the cyst lining is usually located in the deep dermis and does not show any epidermal connection, it may not be clinically identified as a tumor. A sudden increase in the size of a long-standing cyst can serve as a useful indicator of an underlying neoplastic change. Although epidermoid cysts are mostly benign, a thorough histopathological evaluation of all suspected cysts, especially those which have increased in size recently, should be performed to exclude malignant transformation.
Complete excision is the appropriate treatment for cysts with malignant transformation. Incomplete excision may result in recurrence in 30–50% of the cases. Hence, patients should be followed up periodically for possible local recurrence.
Declaration of patient consent
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.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
| References|| |
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[Figure 1], [Figure 2]