Journal of Cancer Research and Therapeutics

: 2014  |  Volume : 10  |  Issue : 3  |  Page : 767--769

Malignant proliferating trichilemmal tumor: A case report and review of literature

Bhakti D Deshmukh, Medha P Kulkarni, Yasmin A Momin, Kalpana R Sulhyan 
 Department of Pathology, Government Medical College, Miraj, Maharashtra, India

Correspondence Address:
Dr. Bhakti D Deshmukh
Department of Pathology, Government Medical College, Pandharpur Road, Miraj - 416 410, Maharashtra


Proliferating trichilemmal tumor (PTT) is an uncommon appendageal skin tumor that affects mainly elderly women. It arises from the external root sheath of the hair follicle and is most commonly observed on the scalp. Although most cases pursue a favorable clinical course and surgical excision is curative, malignant transformation has rarely been reported in these lesions. Because of limited number of cases reported in the literature, management of malignant PTT is controversial and mainly entails wide local excision. Many other adjuvant modalities have been tried. In this report, we present a case of malignant PTT in a 65-year-old male patient who presented with ulceroproliferative growth over occipital region since 4 months.

How to cite this article:
Deshmukh BD, Kulkarni MP, Momin YA, Sulhyan KR. Malignant proliferating trichilemmal tumor: A case report and review of literature.J Can Res Ther 2014;10:767-769

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Deshmukh BD, Kulkarni MP, Momin YA, Sulhyan KR. Malignant proliferating trichilemmal tumor: A case report and review of literature. J Can Res Ther [serial online] 2014 [cited 2019 Oct 14 ];10:767-769
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Proliferating trichilemmal tumour (PTT) is a rare tumor of external root sheath derivation and in most instances appears to develop within the wall of pre-existing pilar cyst. More than 80% of the patients are elderly women. About 90% of the cases occur on the scalp. The tumor shows abrupt keratinization without intervening granular cell layer (trichilemmal keratinization). Most of these neoplasms are benign; however, malignant transformation is reported in literature. Only 39 well-documented cases of malignant proliferating trichilemmal cyst have been published to date in the English language literature. [1]

 Case Report

A 65-year-old man presented with a gradually increasing, painless nodular swelling over scalp since 4 months, which ulcerated 1 month back with bloody discharge. There was no history of trauma or similar lesion in the past. On examination, there was a 3 × 2 cm fungating growth over the occipital region, unfixed to the underlying bone. There was no evidence of regional lymph node enlargement. An incisional biopsy was done and the diagnosis of malignant PTT was given. A wide local excision of the growth was performed later.

Histopathological examination of the incisional biopsy showed a skin covered irregular lobulated mass measuring 1.5 × 1 × 0.5 cm with surface ulceration. Microscopically, the dermis showed a cellular tumor composed of lobules and sheets of squamous cells [Figure 1]. The cells were moderately pleomorphic with hyperchromatic nuclei and high mitotic activity with abnormal mitotic figures [Figure 2]. The tumor lobules showed abrupt keratinization [Figure 3]. Multinucleated tumor giant cells and foci of invasion into surrounding tissue were evident. The diagnosis of malignant proliferating trichilemmal tumor (MPTT) was made. The histopathological examination of wide local excision specimen showed similar tumour morphology, thus confirming the diagnosis of MPTT. The resected margins were free of tumor.{Figure 1}{Figure 2}{Figure 3}

The chest roentgenogram and ultrasound of abdomen were normal.


The tumors of adnexal components of skin are exceptionally rare and were first reported by Wilson-Jones [2] as an entity which can simulate squamous cell carcinoma. Proliferating trichilemmal cyst is a rare but morphologically distinctive tumor usually occurring in the scalp of elderly women. Lanugo hair follicles of bald scalp and follicles of other areas devoid of nonterminal hair are unlikely to produce these tumors. [3] It has been reported under a variety of names including giant hair matrix tumor, invasive pilomatrixoma, proliferating epidermoid cyst, pilar tumor of the scalp, trichilemmal pilar tumor, trichochlamydocarcinoma, proliferating trichilemmal cyst, PTT, and proliferating follicular cystic neoplasm. [4]

MPTT, originally described in1983 by Saida et al., [3] is the rarest of trichilemmal tumors. The biological behavior still remains controversial. MPTT can occur de novo but most often arises in a pre-existing benign proliferating trichilemmal cyst, the malignant transformation being in stepwise manner from adenomatous to epitheliomatous to carcinomatous stage. [3] There is no immunohistochemical marker to detect this malignant transformation however, unlike PTT, there is loss of CD34 expression. Increased proliferation index and DNA aneuploidy in tumor cells may suggest premalignant nature. [5] Clinically, sudden enlargement of long-standing scalp nodule and histologic evidence of abnormal mitoses, marked nuclear atypia, and infiltrative margins reflect malignant transformation. [6] The distinguishing feature of the malignant tumor is the presence of a frankly invasive component along with classical trichilemmal keratinization. Vascular and/or perineural invasion may be observed. The real incidence of a malignant proliferating trichilemmal cyst is unknown, due to its rarity and inconsistencies in nomenclature and misclassification as squamous cell carcinoma.

Ye et al., [7] studied 76 patients and categorized them into three groups. Group 1 tumors were well-circumscribed, showing trichilemmal keratinization and focal nuclear atypia with surrounding tissue showing infiltration by plasma cells, mononuclear cells, and giant cells. These tumors behaved in benign fashion. Group 2 tumors were early invasive with moderate cytological atypia, foci of single cell necrosis, and abrupt keratinization, with a desmoplastic stromal response. These were considered locally aggressive. Group 3 tumors were invasive with marked cytological atypia and desmoplastic stroma, hence were considered malignant. Our case showed Group 3 features.

Kim et al., [8] showed that MPTT can manifest as either a cystic or solid mass on imaging studies. Cystic tumor is typically benign-looking on computed tomography (CT) scan. Malignant radiographical characteristics include poorly defined margins, penetration of the tissue planes, and local invasion into the calvaria, meninges, and dural sinuses. CT is the technique of choice to monitor bony erosion, whereas magnetic resonance imaging would be more suitable to assess soft tissue infiltration and dural involvement. Smooth soft-tissue elevations from the inner wall of the mass are an important clue in predicting the nature of the mass as these areas correspond histologically to proliferating lobules of epithelium, characteristic of MPTT.

The features favoring the diagnosis of MPTT over squamous cell carcinoma are presence of trichilemmal keratinization, lobular growth pattern, and lack of precursor epidermal lesion like actinic keratosis. Since, MPTT has tendency to metastasize and recur more frequently than Squamous Cell carcinoma, accurate diagnosis is essential. [6]

MPTTs are primarily local; hence, adequate wide surgical excision remains the mainstay of treatment. The patient should be followed closely after surgery. Patients presenting with large fungating masses along with regional nodal metastasis can show aggressive behavior and merit aggressive treatment. [9] The efficacy of alternative treatments for malignant cases cannot be safely evaluated in view of the small number of published cases.

Though the experience is limited, the features of ominous significance include clinical findings such as rapid increase in size, tumour size more than 5 cm, nonscalp location and/or foci of necrosis, or ulceration in addition to histological findings of marked cytological atypia and abundant mitotic figures including atypical forms. [10]

In summary, MPTT is a rare malignant lesion and poses a diagnostic dilemma. Though wide surgical excision should be considered as the primary modality of treatment, long-term follow up is required and alternative therapies need further evaluation.


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