|LETTER TO THE EDITOR
|Year : 2015 | Volume
| Issue : 2 | Page : 496-497
A rare case of melanotic malignant trichoblastoma
Y Sunil Kumar1, BK Sathish Chandra2, S Girish3, Shubha Bhat1, Anne George3
1 Department of Pathology, K. S. Hegde Medical Academy, Deralakatte, Mangalore, Karnataka, India
2 Department of Plastic Surgery, K. S. Hegde Medical Academy, Deralakatte, Mangalore, Karnataka, India
3 Department of Dermatology, K. S. Hegde Medical Academy, Deralakatte, Mangalore, Karnataka, India
|Date of Web Publication||7-Jul-2015|
Y Sunil Kumar
Department of Pathology, K. S. Hegde Medical Academy, Deralakatte, Mangalore, Karnataka
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Kumar Y S, Sathish Chandra B K, Girish S, Bhat S, George A. A rare case of melanotic malignant trichoblastoma. J Can Res Ther 2015;11:496-7
Trichoblastoma is a rare benign trichogenic tumor with epithelial and mesenchymal components resembling the germinal hair bulb and associated mesenchyme.  Melanotic/pigmented variant of malignant trichoblastoma (MMT) is a rarity and less reported in world literature.  We present a case of MMT in a 45-year-old female. There is a need to differentiate this tumor from other pigmented tumors due to its aggressive course and specific management. 
A 45-year-old female presented with a painless, pigmented plaque on the left upper lip since childhood [Figure 1]a. There was no sudden increase in size or change in color. Clinically, basal cell carcinoma (BCC), malignant melanoma and melanocytic nevi were considered. Wide excision was performed and microscopy showed thinned out epidermis with focal ulceration [[Figure 1]b]. The tumor cells were arranged in follicular pattern involving the dermis and subcutaneous tissue [[Figure 1]c]. They had pleomorphic bizarre nuclei, prominent eosinophilic nucleoli, increased mitosis with intracytoplasmic melanin pigment infiltrating the subcutaneous and muscular tissue [Figure 1]d. Immunohistochemistry showed positivity for CK 6, 8, 14 and 17 and negativity for HMB-45 (melanocytic marker), which confirms trichogenic differentiation. Final diagnosis of MMT was made. The patient is doing well after 2 year follow-up without any recurrence/metastasis.
|Figure 1: (a) Clinical photograph highlighting the ulcerated pigmented plague on the left upper lip. (b) Microphotograph showing epidermal thinning with ulceration and tumor cells arranged in nests and follicles in the dermis (H and E, ×10). (c) High power view showing the follicular differentiation of the tumor cells (H and E, ×45). (d) Pleomorphic tumor cells infiltrating the subcutaneous tissue and muscle (H and E, ×10)|
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Trichoblastomas are usually solitary, small and well-circumscribed lesions that occur in the deep dermis and subcutaneous tissue on any hair bearing location. The preferred sites include head (especially face and scalp), neck, trunk, proximal extremities and rarely perianal region. ,,, This condition was defined as tumor of hair germ by Headington in 1970.  Later he subdivided into three types i.e. trichogenic trichoblastoma (predominance of epithelial component), trichogenic fibroma (stromal predominance) and trichogenic myxoma (myxomatous stroma). Ackerman's later classified into five histopathologic patterns such as large nodular (including pigmented), small nodular, cribriform, racemiform, and retiform types. 
The latest classification includes subcutaneous, pigmented, clear cell, sebaceous and sweat gland differentiation. Our case was a pigmented type with malignant transformation. They can occur at any age, but are more common in adults (5 th -7 th decades) and have no sex predilection.  The stroma resembles perifollicular fibrous sheath and show focal aggregation to the periphery of basaloid nests resembling papillary mesenchymal body.  Usually, most trichoblastomas develop into primitive hair follicle differentiation. Rare cases may show apocrine and sebaceous differentiation. The close differential diagnosis is pigmented BCC. The lack of epidermal origin, more conspicuous stroma with prominent papillary mesenchymal bodies and absence of retraction artefact are useful diagnostic features in excluding BCC.  The pigmentation in the BCC is restricted to the upper part of dermis unlike the MMT, which is deeper. The prognosis of MMT is much worse compared to BCC due to its locally aggressive nature, recurrence and metastatic potential. Wide surgical excision with normal free margins is the treatment of choice of MMT. Hence, it's highly significant to consider this as a differential diagnosis for all the pigmented lesions, especially in the head and neck region for appropriate management of the patient.
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