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E-IJD-CASE REPORT
Year : 2015  |  Volume : 60  |  Issue : 1  |  Page : 104
A large proliferating trichilemmal cyst masquerading as squamous cell carcinoma


1 Department of Pathology, Jawaharlal Nehru Medical College, Aligarh Muslim University, Aligarh, Uttar Pradesh, India
2 Department of Plastic Surgery, Jawaharlal Nehru Medical College, Aligarh Muslim University, Aligarh, Uttar Pradesh, India

Date of Web Publication26-Dec-2014

Correspondence Address:
Kanupriya Gupta
Flat no D-6 (b), 4th floor, Rifa Complex, Medical Road, Aligarh - 202 002, Uttar Pradesh
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0019-5154.147854

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   Abstract 

Proliferating trichilemmal cyst (PTC), a rare benign tumor, is a fascinating follicular neoplasm. It occurs on head and neck region of elderly women and its histologic hallmark is trichilemmal keratinization. A 70-year-old female presented to skin outpatient department with complaints of a slowly growing mass on scalp for the past 2 years. On examination, the lesion was firm, mobile, painless, and measured 6 × 5 × 3 cm and was not fixed to the underlying bone. Laboratory investigations were unremarkable. Excisional biopsy was done. Histopathology revealed well-demarcated tumor with variably sized lobules of squamous epithelium undergoing an abrupt change into eosinophilic amorphous keratin without granular cell layer (trichilemmal keratinization). PTC should be differentiated from trichilemmal cyst as it has potential for malignant transformation. Thus, complete excision is recommended for all benign proliferating variants owing to their potential for locally aggressive behavior and malignant transformation.


Keywords: Histopathology, proliferating trichilemmal cyst, scalp


How to cite this article:
Alam K, Gupta K, Maheshwari V, Varshney M, Jain A, Khan AH. A large proliferating trichilemmal cyst masquerading as squamous cell carcinoma. Indian J Dermatol 2015;60:104

How to cite this URL:
Alam K, Gupta K, Maheshwari V, Varshney M, Jain A, Khan AH. A large proliferating trichilemmal cyst masquerading as squamous cell carcinoma. Indian J Dermatol [serial online] 2015 [cited 2020 Feb 20];60:104. Available from: http://www.e-ijd.org/text.asp?2015/60/1/104/147854

What was known?
Proliferating trichilemmal cyst is a rare benign tumor.



   Introduction Top


Proliferating trichilemmal cyst (PTC), also known as pilar tumor, is a rare benign skin neoplasm with outer root sheath differentiation. [1] This neoplasm was first recognizedby Wilson-Jones in 1966 as an entity that had the histologic capacity to simulate squamous cell carcinoma. Different terminologies have been used to describe this tumor, pilar tumor of the scalp, PTC, giant hair matrix tumor, hydatidiform keratinous cyst, trichochlamydocarcinoma, and invasive hair matrix tumor. [2] It mainly occurs on the scalp in elderly women [2] and its histological hallmark is the presence of trichilemmal keratinization.


   Case Report Top


A 70-year-old female presented to skin outpatient department with complaint of a slowly growing mass on the scalp for the past 2 years [Figure 1]. The patient was otherwise healthy with no significant medical history. No history suggestive of trauma and chronic irritation except hair combing was present. On examination, the lesion was firm, mobile, painless, and measured 6 × 5 × 3 cm and was not fixed to the underlying bone. There was no regional lymphadenopathy. Systemic examination was normal. Chest roentgenogram did not reveal any evidence of pulmonary metastasis. Contrast-enhanced computed tomography scans of the brain also did not show any evidence of intracranial invasion. Laboratory investigations were unremarkable. Excisional biopsy was done and histopathology revealed well-demarcated tumor with variably sized lobules of squamous epithelium [Figure 2] undergoing an abrupt change into eosinophilic amorphous keratin without granular cell layer (trichilemmal keratinization) with formation of parakeratotic cells without granular cell layer [Figure 3]. Glycogen-rich vacuolated cells were also seen [Figure 4]. The diagnosis of proliferating trichilemmal tumor (PTT) was made.
Figure 1: Clinical picture showing firm, vascular mass in right occipital region (6 × 5 × 3 cm)

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Figure 2: Variably sized lobules of squamous cells with central keratinization (H and E, ×40)

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Figure 3: Proliferating squamous cells with trichilemmal keratinization (H and E, ×00)

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Figure 4: Lobules of clear cells (H and E, ×40)

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   Discussion Top


It is believed that PTC has an association with pilar cysts which are sometimes observed to precede or accompany these tumors but some PTCs arise de novo. [3] The majority of cases, about 90%, occur on the scalp with remaining 10% occurring mainly on the back. There is marked female predominance of 6:1, mostly in elderly women. [4] Starting as a subcutaneous nodule, it may be misdiagnosed as epidermal or trichilemmal cyst. It may slowly grow into a large, solitary, well-circumscribed mass. Sometimes, it may become ulcerated and infected and may resemble squamous cell carcinoma. [2] It can be differentiated from squamous cell carcinoma by the abrupt mode of keratinization, trichilemmal differentiation, the presence of clear cells resulting in glycogen storage and most importantly, a sharp demarcation without infiltration into surrounding structures. [5] PTT shows features of typical pilar cyst, but additionally shows extensive epithelial proliferation, variable cytologic atypia and mitotic activity. PTT is usually benign and rarely may undergo malignant transformation in a step-wise manner starting with an adenomatous stage of the trichilemmal cyst to an epitheliomatous stage of the PTT evolving into the carcinomatous stage of the malignant PTT, which is main consideration in the differential diagnosis. [6] The distinguishing feature of the malignant tumor is the addition of a frankly invasive component that may retain a clear cell pattern with classical trichilemmal keratinization. Nuclear and mitotic activities are variable. Vascular and/or perineural invasion may also be observed. [5] Thus, complete excision is recommended for all benign proliferating variants owing to their potential for locally aggressive behavior and malignant transformation.

 
   References Top

1.
Leppard BJ, Sanderson KV. The natural history of trichilemmal cysts. Br J Dermatol 1976;94:379-90.  Back to cited text no. 1
    
2.
Brownstein MH, Arluk DJ. Proliferating trichelemmal cyst: A simulant of squamous cell carcinoma. Cancer 1981;48:1207-14.  Back to cited text no. 2
    
3.
Poiares Baptista A, Garcia E Silva L, Born MC. Proliferating trichilemmal cyst. J Cutan Pathol 1983;10:178-87.  Back to cited text no. 3
    
4.
Morgan RF, Dellon A, Hoopes JE. Pilar tumors. Plast Reconstr Surg 1979;63:520-4.  Back to cited text no. 4
    
5.
Chikhalkar S, Garg G, Gutte R, Khopkar U. Sebaceous carcinoma of scalp with proliferating trichilemmal cyst. Indian Dermatol Online J 2012;3:138-40.  Back to cited text no. 5
[PUBMED]  Medknow Journal  
6.
Rao S, Ramakrishnan R, Kamakshi D, Chakravarthi S, Sundaram S, Prathiba D. Malignant proliferating trichilemmal tumour presenting early in life: An uncommon feature. J Cutan Aesthet Surg 2011;4:51-5.  Back to cited text no. 6
[PUBMED]  Medknow Journal  

What is new?
The large size of the lesion and it was clinically confused with squamous cell carcinoma.


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4]



 

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