Malignant proliferating trichilemmal tumor of the scalp: A case report
Published Web Locationhttps://doi.org/10.5070/D343f7r58v
Malignant proliferating trichilemmal tumor of the scalp: A case report1. Department of Pathology, Farhat Hached hospital, Sousse, Tunisia. email@example.com
Amel Trabelsi MD1, Wided Stita MD1, Olfa Gharbi MD2, Nesrine Kanani MD1, Badreddine Sriha MD1, Sadok Korbi MD1
Dermatology Online Journal 14 (8): 11
2. Department of Cancerology, Farhat Hached Hospital, Sousse, Tunisia
BACKGROUND: Malignant proliferating trichilemmal tumor is a rare skin tumor that affects mainly older women. It mimics squamous cell carcinoma and its biological behavior is unpredictable. OBJECTIVE: To report on a new case of malignant proliferating trichilemmal tumor of the scalp and to describe the clinical and histopathologic findings. METHODS: A tumor measuring 2cm was surgically excised with a 0.5cm conservative margin of normal tissue RESULTS: Based on the histopathologic findings of the tumor, this case was diagnosed as proliferating trichilemmal tumor of the scalp. Eleven months after tumor resection, the patient is free of disease. CONCLUSION: Malignant proliferating trichilemmal tumor is a rare malignant lesion with an unpredictable biological behavior. After wide excision, long term clinical follow up of the patient for early diagnosis of metastases is judicious.
Malignant proliferating trichilemmal tumor (MPTT) is a rare skin tumor that arises in the sun-exposed areas of elderly women. It mimicks squamous cell carcinoma and its biological behavior is unpredictable. We report a new case and discuss the clinicopathologic features of this rare entity.
A 76-year-old woman, without remarkable previous medical or family history, presented with a recent, rapidly-growing, painless, nodule (2cm x 1cm) on the scalp. The tumor was resected with a 0.5cm free margin of normal tissue. Grossly, the excised specimen consisted of a well-circumscribed mass that measured 2cm x 1cm. The cut surface revealed a grey-tan tumor with multiloculated cystic spaces filled with yellow-tan fluid.
|Figure 1||Figure 2|
|Figure 1. Area of ordinary proliferating trichilemmal tumor with trichilemmal keratinization (HE, x200)|
|Figure 2. Malignant component with an infiltrative growth and cellular atypia (HE, x400)|
|Figure 3. Malignant component with abnormal mitoses (HE, x400)|
Microscopically, the tumor showed an ordinary proliferating trichilemmal tumor (PTT), characterized by a circumscribed lobular proliferation of keratinocytes surrounding a central zone of trichilemmal-type keratinous material (Fig. 1). These areas of typical PTT were juxtaposed with zones that displayed marked nuclear irregularity with mitotic activity (Fig. 2) and an infiltrative growth pattern (Fig. 3). Based on these findings, the diagnosis of MPTT was made.
Malignant proliferating trichilemmal tumor is an uncommon cutaneous neoplasm that has been the subject of controversy in the dermatology literature . The term MPTT was entered in the literature by Saida et al. in 1983  because of a proliferating trichilemmal tumor that showed infiltrative growth, marked cytologic atypia, high mitotic activity including atypical forms, and lymph node metastases .
The differential diagnosis of MPTT includes squamous cell carcinoma. Features favoring the diagnosis of MPTT including the scalp location, the presence of trichilemmal type keratinization, and the lack of a precursor epidermal lesion such an actinic keratosis .
Malignant proliferating trichilemmal tumor must be differentiated from trichilemmal carcinoma. MPTT is a lobular proliferation centered around the pilosebaceous unit and composed of clear cells with basilar or full thickness interfollicular epidermal spread, there is always connection to the epidermis .
Wide local excision with a 1cm margin of normal tissue is the appropriate treatment . Chemotherapy and radiotherapy have been used by some authors in addition to local excision to prevent recurrence . Malignant proliferating trichilemmal tumor has greater malignant potential than histologically similar cutaneous squamous cell carcinoma , particularly tumors greater than 5cm or with spindle cell components .
Malignant proliferating trichilemmal tumor is a rare malignant lesion with an unpredictable biological behavior. Long term clinical follow-up is judicious to detect recurrence or metastases.
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