Indian Journal of Pathology and Microbiology
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Year : 2009  |  Volume : 52  |  Issue : 2  |  Page : 277-278
Solitary trichoblastoma

Department of Pathology, NKP Salve Institute of Medical Sciences, Digdoh Hills, Hingna, Nagpur - 440 019, India

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How to cite this article:
Karmarkar PJ, Mahore SD, Wilkinson AR. Solitary trichoblastoma. Indian J Pathol Microbiol 2009;52:277-8

How to cite this URL:
Karmarkar PJ, Mahore SD, Wilkinson AR. Solitary trichoblastoma. Indian J Pathol Microbiol [serial online] 2009 [cited 2020 Apr 8];52:277-8. Available from: http://www.ijpmonline.org/text.asp?2009/52/2/277/48947


A 52-year-old male patient presented with a complaint of a large swelling in the suprapatellar region. This was progressively increasing in size over 3 years. On examination, the swelling was round to oval, well circumscribed, freely mobile, with a firm to hard consistency. No other masses or lymph nodes were palpable. A clinical diagnosis of fibroma was made. The mass was excised completely and sent for histopathological examination.

Gross examination revealed a well-circumscribed, non-encapsulated mass measuring 6.6cm 4cm 2cm, of firm to hard consistency. A cut section revealed a well-circumscribed, non-encapsulated, lobulated grayish white mass, with small focal areas of calcification [Figure 1]. Microscopic examination showed a well-circumscribed mass of epithelial cells arranged in lobules, sheets and nests with variable amount of stroma. Tumor cells were small, basophilic with scanty cytoplasm and showed peripheral palisading [Figure 2]. At places, the lobules showed formation of keratin cysts and focal clear cell change. The stroma was fibromyxoid and composed of both spindle and stellate cells. A few areas of pigmentation and focal calcification were also seen. The tumor involved the dermis and was reaching up to the subcutaneous tissue. There was no connection of the tumor with the overlying normal epidermis. A histopathological diagnosis of trichoblastoma of the suprapatellar region was given.

Trichoblastoma is a rare, benign, slow-growing tumor showing differentiation toward the primitive hair follicle. It presents clinically as a slowly growing, solitary, well-circumscribed nodule, located predominantly in the head and neck with predilection for the scalp. The trunk, proximal extremities and the perianal and genital regions may also be affected. It is rarely encountered in the distal extremities. Any age group except young children is affected, with most patients in the fifth to seventh decade. [1] They usually grow up to 3cm, with a few cases reaching 8-10cm in size.

Histologically, trichoblastoma is a well-circumscribed, nodular tumor spanning the entire dermis, characteristically extending into the subcutaneous tissue. A purely subcutaneous location may be rarely seen. [2] It is characterized by variable-sized epithelial nests, conspicuous peripheral palisading and stromal condensation around the tumor lobules closely resembling basal cell carcinoma. Other features include keratinous cyst formation, prominent fibromyxoid change in the stroma, clear cell change in the epithelium and foci of calcification. A few areas of pigmentation may be seen. A pigmented variant of trichoblastoma called melanotrichoblastoma has also been reported. [3]

Trichoblastomas are most commonly mistaken for conventional trichoepithelioma and basal cell carcinoma. Trichoblastoma is much larger than the conventional trichoepithelioma and situated in the deep dermis and subcutaneous tissue while the latter is centered in the middermis.

Trichoblastoma shows less keratinization and is devoid of epidermal or follicular origin. Lack of epidermal origin, more conspicuous stroma with prominent papillary mesenchymal bodies and absence of retraction artifacts are useful diagnostic features in excluding basal cell carcinoma. It is often extremely difficult to make this distinction, especially on a small biopsy. Hence, complete excision is the treatment of choice. The patient is being followed-up and is well 2 years after surgery.

   Acknowledgement Top

We thank Dr. Jayant Karmarkar, Consultant Surgeon, Nagpur, for giving us this interesting case to study.

   References Top

1.Brenn T, Mackee PH. Tumors of the hair follicle. In: Mackee PH, Calonje E, Granter SR, editors. Pathology of the skin with clinical correlations.3 rd ed. Elsevier Mosby; 2005. p. 1552-7.  Back to cited text no. 1    
2.Kadu S, Schaeppi H, Kerl H, Soyer HP. Subcutaneous trichoblastoma. J Cutan Pathol 1999;26:490-6.  Back to cited text no. 2    
3.Kanitakia J, Brutzkus A, Butnaru AC, Claudy A. Melanotrichoblastoma: immunohistochemical study of a variant of pigmented trichoblastoma. Am J Dermatopathol 2002;24:498-501.  Back to cited text no. 3    

Correspondence Address:
Anne R Wilkinson
Department of Pathology, NKP Salve Institute of Medical Sciences, Digdoh Hills, Hingna, Nagpur - 440 019
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0377-4929.48947

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  [Figure 1], [Figure 2]

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