Proliferating trichelemmal cyst: mimicking squamous cell carcinoma in a 12 year old male child

Proliferating trichelemmal cyst: mimicking squamous cell carcinoma in a 12 year old male child
Proliferating trichelemmal cyst: mimicking squamous cell carcinoma in a 12 year old male child

India, June 12

Abstract

Proliferating trichilemmal cyst (PTC) is anuncommon neoplasm of hair follicular cells in origin. It occurs most commonly on head and neck region of elderly women. Its histological hallmark is the presence of trichilemmal keratinization without interposed granular layer. Here we describe a case of PTC in a 12 year old child which was mimicking squamous cell carcinoma both clinically as well as histologically.

Key words: proliferating trichilemmal cyst; abrupt keratinization, squamous cell carcinoma.

Introduction

Proliferating trichilemmal cyst (PTC) is a relatively uncommon benign skin neoplasm of external root sheath derivative [1]. In 1966 WilsonJones first describe this entity that had histological similarity with squamous cell carcinoma (SCC) [2]. A diverse alternatives have been used to supplement this neoplasmas proliferating epidermoidcyst, pilar tumor of the scalp, proliferating trichilemmal cyst, proliferating epidermoid cyst, giant hair matrix tumor, hydatidiform keratinous cyst, trichochlamydocarcinoma, and invasive hair matrix tumor [3]. It most commonly occurs in elderly women with very high predilection for scalp [4]. Histologically it show the presence of trichilemmal type of keratinizationwithout interposed granular layer [5].A case of PTC in 12 years old male child which was clinically diagnosed as SCC is being reported herein.

Case report

A 12yearold male child presented to surgery outpatient departmentwith the complaint of a slowly growing mass on the scalp since 1 year. The patient was healthy and hasa medical history of electric shockat the same site of the lesion one and half years back. On examination, the lesion was fungating and cauliflower like with central ulceration [figure 1].It was mobile,painless and measured 2.5X2cm. It was not fixed to theunderlying bone. Initially the lesion was soft to firm in consistency, painless and mobile.There was no regional lymphadenopathy.On systemic examination, no abnormalities was detected. Chest roentgenogram and Contrastenhanced computed tomography scans of the braindid not reveal any evidence of metastasis and invasion respectively.Laboratory investigations were unremarkable. Clinical diagnosis of SCC was made. Wide local excision biopsy was done and the specimen was received for histopathology. Grossly a grey brown soft tissue measuring 3X2.5X2 cm was received. A fungating and ulcerated growth was present in the center measuring 2.5X2.5X2 cm. Cutsections the lesion was grey white in colour [Figure 2]. Microscopic examination revealed welldemarcatedtumor within the dermis with variably sized lobules and trabeculae of squamous epithelium [figure 3]. There was focal moderate nuclear pleomorphism and brisk mitotic activity. Few cells showing clear cell change, dyskeratosis and focal area of trichilemmal type of keratinization were present [figure 4]. No necrosis, no lymphovascularinvasion or invasion of adjacent structures was seen. The diagnosis of proliferatingtrichilemmal tumor (PTT) was made.

Figure 1: Photomicrograph showing clinical& gross picture of proliferating trichilemmal cyst.

Figure 2: Photomicrograph showing well circumscribed lesion of squamoid cell in the dermis.

Figure3: Photomicrograph showing clear cell and abrupt keratinization in the lesion.

Discussion

Pilar tumors are very rare skin adenexal skin neoplasm (0.1%)[1]. PTT seems to have an association with withtrichelimmal cyst but it may arise de nova [6]. It most commonly occurs as scalp lesion approximately 90% remaining 10% occurs on the neck, trunk, armpits, groin,

vulva, lower and upper limbs, upper lip and buttocks [4,7,8]. It has very high female to male preponderance (6:1), most commonly in elderly female [4]. Initially it may presented as subcutaneous nodule. It may gradually increases in size to large, solitary and pedunculated mass sometime it may ulcerated and infected mimicking squamous cell carcinoma [3]. Histologically it may be differentiated from SCC by well circumscribed lesion in the dermis, presence of trichilemmal type of keratinization (abrupt transition of squamous epithelial layer to keratin layer without interposed granular layer) and presence of clear looking squamoid cell due to glycogen storage [9]. It can be differentiated from pilar cyst by the presence of nests and lobules of squamoid and basaloid cell in the dermis with the features of trichilemmal type of keratinization and associated with varying degree of cytological atypia and mitotic activity[10]. PTT has different stages of oncogenic transformation starting with an adenomatous stage of the trichilemmal cyst to an epitheliomatousstage of the PTT evolving into the carcinomatous stage of the malignant PTT [10].

Clinicopathologically PTT is divided into benign, low and high grade malignant on the basis of stromal invasion, level cytological atypia, mitoticactivity and vascular and perineural invasion[11]. Low grade PTT have a potential of recurrence but show no metastasis while malignant PTT show both recurrence and metastasis, benign lesions are free of metastasis and recurrence [11]inspite of this PTC should be differentiated from benign adnexal lesion e.gpilar cyst due to its potential of malignant transformation [12].In view of this wide local excision is recommended in all benign proliferating lesion due to its locally aggressive behavior and malignant transformation [12]. Mohs micrographic surgery may be done to reduce the recurrence and metastasis rate after tumor resection [13].

References

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  2. Wilson-Jones E. Proliferating epidermoid cysts. Arch Dermatol. 1966; 94:11-19.
  3. Brownstein MH, Arluk DJ. Proliferating trichelemmal cyst: A simulant of squamous cell carcinoma. Cancer 1981; 48:120714.
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  11. Ye J, Nappi O, Swanson PE, Patterson JW, Wick MR. Proliferating PilarTumors: A Clinicopathologic study of 76 cases with a proposal for definition of benign and malignant variant. Am J Clinpathol. 2004; 122: 566-74.
  12. KiranAlam, Kanupriya Gupta, VeenaMaheshwari, ManoranjanVarshney, Anshu Jain, Arshad Hafeez Khan. A Large Proliferating Trichilemmal Cyst Masquerading as Squamous CellCarcinoma. Indian J Dermatol 2015;60:104.
  13. Tierney E, Ochoa M, Rudkin G, Soriano TT. Mohs' micrographic surgery of a proliferating trichilemmaltumor in a young man. DermatolSurg 2005; 31:359-63.

Legands

Figure 1: Photomicrograph showing clinical& gross picture of proliferating trichilemmal cyst.

Figure 2: Photomicrograph showing well circumscribed lesion of squamoid cell in the dermis.

Figure3: Photomicrograph showingclear cell and abrupt keratinization in the lesion.

Dr. SatyaDutta; Dr.ShilpaGarg ; Dr. Rahul N Satarkar ; Dr. ShiwaniKalhan; Ashok Sangwaiya; ShilpaTomar. Department of Pathology, SHKM, Nalhar, Mewat, Haryana

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