Pilomatrix carcinoma

Case reports

370

Pilomatrix carcinoma P. Vico*, I. Rahiert G. Ghanem:l:P. Nagypal* and R. Deraemaecker* *Department of Surgery, ~fDepartment of Pathology, lnstitut Jules Bordet, Centre des Tumeurs de I'Universit~ Libre de Bruxelles, Brussels, Belgium; ~Laboratory of Experhnental and Oncologic Surgeon, lnstitut Jules Bordet, Facult~ de M~decine, Universit~ Libre de Bruxelles, Brussels, Belgium

A 43-year-old man presented with a tumour of the medial part of the right eyebrow. A biopsy was performed and histological examination revealed a malignant transformation of a 'calcifying epithelioma of Malherbe'. A secondary wide excision was performed. Clinical and pathological findings of this extremely rare tumour are reviewed. Factors inflhencing the prognosis are proposed, based on a compilation of the literature.

Key words:pilomatrix.

Introduction In 1880, Malherbe described a skin appendage tumour called "calcifying epithelioma of Malherbe', 'pilomatrixoma' or 'trichomatricoma'. It develops at the hair matrix as a slow-growing tumour, usually in the head and neck area. Sixty per cent of these tumours appear before the age of 30. It may be associated with Gardner syndrome and myotonic muscular dystrophy) Recurrences after surgical treatment are rare, and malignant behaviour was reported in 54 cases: 40 cases with local recurrences and four cases with metastases.

Case report A 43-year-old man presented with an indolent and slow-growing mass in the medial part of the right eyebrow, which had been present for many years. He complained of irradiating pain in the right frontoparietal scalp. Clinically the mass was firm, reddish and painful with a diameter of 8 mm. Clinically it appeared as an epidermal inclusion cyst and the lesion was enucleated under local anaesthesia. Gross examination was irrelevant, but histology led to the diagnosis of pilomatrix carcinoma. Two weeks later, a wide excision (margins of 5mm) was performed under local anaesthesia. Histological controls showed no residual tumour. The patient is 25 months follow-up, with no evidence of local recurrence or metastasis. Chest X-ray is normal.

Pathological findings This rare malignant tumour appears usually macroscopically as a nodule between 1 and 1.5cm (Fig. I). Most of the histopathology o f this lesion resembles the benign pilomatricoma with proliferation of the basaloid cells, shadow cells and fibrotic and granulomatous stromal responses. In the malignant counterpart the basaloid component demonstrates numerous mitotic figures among which atypical mitoses are found (Fig. 2). Two other features of malignancy are cellular necrosis and stromal infiltration at the periphery by atypical basaloid epithelium. In our case no stromal infiltration was observed, but necrosis and atypic nuclei suggest a diagnosis o f malignant insitutransformation.

Correspondence to: P. Vico, Institut Jules Bordet, Centre des Tumeurs de I'Universit6 Libre de Bruxelles, Department o f Surgery, 1, rue H6ger-Bordet, 1000-Brussels, Belgium.

Fig. 1. General aspect of the tumour. Note the absence o f stromal invasion (H&E, x 40, reproduced here at 50'70).

Discussion Malherbe and Chenantais 3 described in 1880 a benign tumour arising from the hair matrix cells and called it a 'calcifying epithelioma'. Its usual behaviour is that of a benign tumour, enlarging slowly, asymptomatic, occurring in young adults, and most often located in the head and neck. Clinically, it is frequently mistaken for an epidermal cyst. Rapid growth has been described? as well as local aggressiveness) and even malignancies. We were able to find 55 cases in the literature, including our own. We compiled the available clinical and histological data of all those cases in order to find any prognostic factors. As those cases come from different parts of the world and were variously treated, it is not an homogenous series, and statistical analysis cannot be used. But several clinical informations can be highlighted. The factors "studied were sex, age, localization, latency before diagnosis, size of the tumour, initial treatment, and number of mitoses, and their eventual relationship with the clinical behaviour of the tumour (recurrence and/or metastases). Sex ratio is approximately 3 males to I female (40 males: 15 females). Mean age is 44 years (median: 45 years, range: 2 to 93). Twenty-three per cent o f the cases occur in individuals younger than 20 years of age. Tumours have been found in all localizations; however 62% are localized in the head, among which 30% are in the pre-auricular area. Local recurrences could be associated with the initial treatment

Case reports

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In conclusion, pilomatrix carcinoma is a rare cutaneous malignancy. The cause of the degenerative behaviour of the common benign calcifying epithelioma of Malherbe is unknown, and is probably multifactorial. Wide excision seems to be associated with a lower rate of local recurrences. This is the case with all cutaneous malignancies and must be a basic principle of treatment. But how wide is wide? Based on our experience with skin carcinoma of head and neck, we chose 5 mm empirically as an adequate margin for facial localization.

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We would like to thank Mrs Kevers-Pion for her bibliographic assistance.

Fig. 2. The basaloid component with severe cytologic atypic aspects (H&E, x 200, reproduced here at 50%).

(simple excision vs wide excision), with the initial tumour size, or with the localization. Simple or wide surgical excision has been the initial treatment in 50 cases. Four other cases were treated by radiotherapy (one case), curettage (one case), and surgery combined with radiotherapy (two cases). Radiotherapy was rarely used and its therapeutic contribution is therefore not evaluable. Definition of wide excision is never precise and therefore the range for surgical margins could be more or less important. Seventeen patients had such a wide excision, while 33 had a simple excision. Three patients recurred locally in the first group, compared with 21 in the second group, 17.6% and 63.6% respectively. Four patients metastasized in the bones (two cases), lungs (two cases) and lymphatic ganglia (one case)] '6-9 The patients with lung and lymphatic ganglia metastases died of the disease 3 years after the diagnosis, the others have been followed-up from between 4 and 13 years. No association could be found between localization and latency before diagnosis, size and recurrences. However, as noted above, wide excision seems to be associated with a lower rate of local recurrence than does simple excision (17.6% and 63.6%, respectively). The number of mitoses do not seem to be associated with latency, size, localization or recurrence of the tumour. (In our cases the number of mitoses was 33 per high-power field ( x 400); range in the literature is 6 to 62).

References 1. Lopanski S, Mihm MC. Pilomatrix carcinoma or calcifying epitheliocarcinoma of Malherbe. A case report and review of literature. Cancer 1980; 45: 2368-73. 2. Gould E, Kurgon R, Kowalezyk AP, Soldana M. Pilomatrix carcinoma with pulmonary metastasis. Report of case. Cancer 1984; 54: 370-2. 3. Malherbe A, Chenantais J. Note sur l'epith61iome calcifi6 des glandes s6bac6es. Prog Med 1980; 8: 826-8. 4. Swerlick RA, Cooper PH, Mackel SE. Rapid enlargement of pilomatricoma. J Am Acad Dermatol 1982; 7: 54-6. 5. Wickremaratchi T, Collins CMP. Pilomatrixoma or calcifying epithelioma of Malherbe invading bone. Histopathology'1992; 21: 79-81. 6. Green DE, Sanusi ID, Fowler MR. Pilomatrix carcinoma. J A m Acad Dermatol 1987; 17: 264-70. 7. Manivel C, Wick MR, Mukai K. Pilomatrix carcinoma: an immunohistochemical comparison with benign pilomatrixoma and other benign cutaneous lesions of pilar origin. J Cutan Pathol 1986; 13: 22-9. 8. O'Donovan DG, Freemont AJ, Adams JE, Markham DE. Malignant pilomatrixoma with bone metastasis. Histopathology 1993; 23: 385-6. 9. Campoy F, Stiefel P, Stiefel E, et al. Pilomatrix carcinoma: role played by MR imaging. Neuroradiology 1989; 31: 196-8.

Accepted for publication 21 April 1996