Indian Journal of Dermatology
E-IJD CORRESPONDENCE
Year
: 2019  |  Volume : 64  |  Issue : 4  |  Page : 339-

Squamous cell carcinoma versus malignant proliferating trichilemmal tumor: A histopathological dilemma with review of literature


Charu Agarwal, Mukta Pujani, Sujata Raychaudhuri, Sheetal Arora, Deepshikha Rana, Varsha Chauhan 
 Department of Pathology, ESIC Medical College, Faridabad, Haryana, India

Correspondence Address:
Charu Agarwal
Department of Pathology, ESIC Medical College, Faridabad, Haryana
India




How to cite this article:
Agarwal C, Pujani M, Raychaudhuri S, Arora S, Rana D, Chauhan V. Squamous cell carcinoma versus malignant proliferating trichilemmal tumor: A histopathological dilemma with review of literature.Indian J Dermatol 2019;64:339-339


How to cite this URL:
Agarwal C, Pujani M, Raychaudhuri S, Arora S, Rana D, Chauhan V. Squamous cell carcinoma versus malignant proliferating trichilemmal tumor: A histopathological dilemma with review of literature. Indian J Dermatol [serial online] 2019 [cited 2022 Jan 25 ];64:339-339
Available from: https://www.e-ijd.org/text.asp?2019/64/4/339/262167


Full Text



Sir,

A 15-year-old female patient presented with intermittent pain over ulcerated lesion on the frontoparietal region of the scalp. She was fine until 6 months back when she started developing multiple ulcers over the frontoparietal area which coalesced to the present size of about 4 cm × 3 cm [Figure 1] with pus-like discharge. She had a history of burn in childhood followed by scarring of the area. An excisional biopsy was performed. Histopathological sections showed tumor comprising of atypical squamous epithelial cells arranged in nests, sheets, and clusters with invasion of subepithelial tissue with abnormal keratinization [Figure 2]a. Numerous keratin pearls and extensive areas of necrosis were seen. Tumor cells were highly pleomorphic with bizarre and atypical mitotic figures [Figure 2]b. A differential diagnosis of squamous cell carcinoma (SCC) and malignant proliferating trichilemmal tumor (MPTT) was considered, and immunohistochemistry (IHC) for calretinin, CD34, Ki67, CK15, and p53 was advised. IHC revealed strong p53 staining [Figure 3]a and Ki67 labeling index of 40% [Figure 3]b; however, calretinin and CD34 came out to be negative, ruling out trichilemmal differentiation and confirming a final diagnosis of SCC.{Figure 1}{Figure 2}{Figure 3}

Proliferating trichilemmal tumor (PTT) is a rare benign neoplasm arising from the isthmus region of the outer root sheath of the hair follicle, comprising of only 0.1% of skin biopsies; however, MPTT is even rarer.[1] It occurs most commonly in elderly female, predominantly on the scalp region. Long-standing burn scars have a high potential for malignant degeneration mainly in the lower and upper extremities (60%) followed by presternal region and rarely in the scalp region or other parts of the body and are seen more commonly in males.[1] Burn scar carcinomas of the scalp account for 14% of burn scar carcinomas.[2] The average latent period for appearance of SCC is 35 years.[3] The present case is a case of SCC in a young female developing over a burn scar in the scalp region with a latent period of about 10 years.

The histological hallmark of PTT is the presence of abrupt trichilemmal keratinization – the sudden transition of a nucleated epithelial cell to an anucleated, amorphous, compact keratinized cell that covers the cyst wall without the formation of granular layer.[4],[5] The present case showed abrupt keratinization along with the presence of squamous cell differentiation thereby creating a dilemma.

IHC plays an important role in differentiating the two entities. On extensive review of literature,[4],[5],[6],[7] as elaborated in [Table 1], it was found that CD34 and calretinin are two important immunohistochemical markers of outer root sheath differentiation, showing positivity in PTT. Proliferation markers such as Ki67 and p53 staining were high in both SCC and malignant PTT. Most PTT showed positive staining for AE13 and AE14, while SCC showed no staining. In the present case, calretinin and CD34 came out to be negative, ruling out trichilemmal differentiation. Cutaneous SCC is treated with surgical excision including Mohs micrographic surgery, with radiotherapy being given in cases of incomplete resection.{Table 1}

The present study highlights the importance of histomorphological features along with IHC to prevent the misdiagnosis of PTT and avoid mistreatment.

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

Nil.

Conflicts of interest

There are no conflicts of interest.

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