|Year : 2014 | Volume
| Issue : 2 | Page : 135-137
Giant trichilemmal cyst on gluteal region
Harsh A Shah1, Atul V Shrivastav2, Neeru M Agarwal1, Nandini J Desai1
1 Department of Pathology, M. P. Shah Medical College, Jamnagar, Gujarat, India
2 Department of Pathology, C. U. Shah Medical College, Surendranagar, Gujarat, India
|Date of Web Publication||11-Aug-2014|
Atul V Shrivastav
Department of Pathology, C. U. Shah Medical College, Surendranagar - 363 001, Gujarat
Source of Support: None, Conflict of Interest: None
Proliferating trichilemmal tumor (PTT) is typically seen in middle aged or elderly patients, with a strong predilection for women and is usually situated in scalp. We are reporting such a tumor located on the gluteal region of a 52-year-old male. The tumor was diagnosed as PTT based on its specific histological features. The case is unusual because of sex of the patient and the tumor location. Moreover, this report illustrates a rare tumor which can be diagnostically challenging. The differentiation between a benign or malignant process in these lesions can sometimes be difficult. Careful clinical and histological assessment is necessary for an accurate diagnosis.
Keywords: Gluteal region, histopathology, proliferating trichilemmal tumor
|How to cite this article:|
Shah HA, Shrivastav AV, Agarwal NM, Desai NJ. Giant trichilemmal cyst on gluteal region. J Mahatma Gandhi Inst Med Sci 2014;19:135-7
| Introduction|| |
Cutaneous cysts represent a large proportion of the specimens submitted for histopathological examination and comprise a wide spectrum of entities. Trichilemmal cyst also known as pilar tumor, is a benign adnexal tumor of skin, related to the isthmus of the hair follicle. Sometimes these cysts can become multiple and progresses rapidly to form large sized proliferating trichilemmal tumor (PTT). Although benign in nature but they can become malignant and produce distant metastasis too. Proliferating trichilemmal tumor (PTT) most commonly occur on the scalp during the fourth to eighth decades of life and have a distinct predilection for women. 
| Case Report|| |
A 52-year-old male patient reported the appearance of a pruritic papule on the gluteal region 1 year ago, which gradually evolved as a tumor, with episodes of bleeding at the site. Primary diagnosis was of epidermal cyst. Dermatological examination showed a pedunculated swelling over left gluteal region with variable consistency; soft at some places and cystic at others. Overlying skin was wrinkled and hyperemic [Figure 1], swelling was not fixed to the underlying structure. Ultrasonography of the local area suggested infected cyst. The pre-operative computed tomography scan revealed a heterogeneous, expansive oval lesion measuring 15.6 cm × 15 cm, with a lobulated shape and rough calcifications. Complete excision of the lesion with a 1 cm conservative margin of normal tissue was performed in our institute.
Histological examination revealed an intradermal proliferation with lobular architecture formed by clusters of pleomorphic epithelioid cells with eosinophilic cytoplasm and nuclear atypia, surrounded by a fibrous pseudocapsule. Microscopically, variably sized lobules composed of squamous epithelial lining, which abruptly changed into eosinophilic keratin in the center of lobules [Figure 2]. Focal areas of calcification, granulomatous foreign body reaction and cholesterol clefts were seen. There was no attachment to underlying muscle tissue and no lymphadenopathy. The tumor presented foci of acantholysis and areas consisting of a set of clear cells with keratinized centers, representing trichilemmal differentiation [Figure 2]. The stroma exhibited numerous vessels and granulation tissue on epidermal hyperplasia. Tumor is graded as benign variety the correlation of clinical findings with histopathology confirmed the diagnosis of PTT.
|Figure 2: A lobule showing squamous lining which abruptly changes into eosinophilic keratin (H and E ×100)|
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| Discussion|| |
PTTs are an aggressive variant of trichilemmal cysts that often affect women over 40; first described as a "proliferating epidermoid cyst" by Wilson Jones in 1963 Since than it has been referred to in the literature by different names: invasive pilomatrixoma, gigantic matrix and keratinizing trichilemmoma.  Originating in the hair isthmus, PTTs are usually solitary and develop in areas with high concentrations of hair follicles, such as the scalp. Other less common locations include the neck, trunk, armpits, groin, vulva, lower and upper limbs, upper lip and buttocks.  Starting as a subcutaneous nodule suggesting of a wen, the tumor may grow into a large, elevated lobulated mass they may undergo ulceration and bleeding and thus resembles a squamous cell carcinoma. 
PTT usually forms a well-circumscribed multilobulated mass in the dermis that is composed of keratinocytes with densely eosinophilic cytoplasm and foci of trichilemmal type of keratinization, which presents as abrupt keratinization in the absence of a granular layer.  The lesion may occasionally exhibit necrosis, a foreign-body giant cell reaction and calcification. In a substantial proportion of cases, nuclear atypia is seen in the proliferating cells as well as brisk mitotic activity. Moreover zones of spontaneous degeneration an calcification may be mistaken for necrosis.  However tumor differs from squamous cell carcinoma by a rather sharp demarcation from the surrounding stroma and its abrupt mode of keratinization.  Local excision of the lesion is the traditionally accepted therapeutic strategy for benign PTTs. The treatment of choice is surgical resection with a safety margin of one centimeter. Adequate excision is required to decrease the recurrence of low-grade malignant PTTs and careful assessment of the surgical margins of the tumor is important.
| Conclusion|| |
The patient described in our study stands out for being a man with presentation of 15 cm × 15 cm giant proliferating trichilemmal cyst in an unusual location. Surgeons should be aware of this entity while differentiating cutaneous cyst located on the gluteal region.
| References|| |
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[Figure 1], [Figure 2]