Desmoplastic Malignant Melanoma: A Case Report

DANIEL MAN, L. J. WEINER, and H. M. REIMAN, Jr.

The Section of Plastic and Reconstructive Surgery, Department of Surgery, University of Louisville School of Medicine, and the Department of Pathology, Norton Hospital, Louisville, Kentucky, USA

Summary -A further case of desmoplastic malignant melanoma of the cheek is presented, bringing the total number of reported cases to 15. Its clinicopathological features and treatment are discussed.

Desmoplastic malignant melanoma is a rare cutaneous tumour. Only 14 cases (Frolow at rll.. 1975; Labrecque et trl., 1976: Valensi, 1977) have been reported since the original description by Conley and his colleagues (1971). We wish to report another case that illustrates the clinical course. histopathology and the surgical management of this rare variant of melanoma.

Case Report

A 50-year-old man was referred with a three month history of a progressively enlarging subcumneous tumour over the left check. The lump was painless and only caused difficulty when shaving. In the skin overlying the mass was a large. stable. darkly pigmented lesion which had been present since birth.

On examination there was an irregularly shaped, flat. brownish-red. pigmented lesion (4 x 3 cm) which ov~crlaid a subcutaneous nodule that measured 4 x 2 y Zcm and had ill-defined margins (Fig. 1). The

tumour was movable, firm and rubbery in consistency. Three lymph nodes were palpable in the left jugulo-digastric chain.

Histnlogical examination of a biopsy from the subcutaneous lesion revealed a neurofibrosarcoma. A wide local excision with superficial parotidectomy and radical neck dissection was performed: histologic examination of the lymph nodes and the parotid gland showed no evidence of any tumour.

Detailed examination of the operative specimen showed that the flat. pigmented lesion on the surface was a typical lent&o maligna with atypical, melanin- c~uitainmg meianocytes at the dermal-epidermal junction (Fig. 2). The underlying nodular lesion had a completely different histological appearance. It was apposed to the overlying lent&o maligna but there was no discernible morphological transition or connection between the cells of the two lesions (Fig. 3).

The underlying nodular lesion consisted of elongated spindle cells arranged in fascicles within a dense fibrous stroma. The cells were pleomorphic and showed abundant mitoses (Fig. 4). Special stains. including Fontana-Masson silver for melanin, Sevier Munger for neural tissue, Wilder’s reticulin, and Masson’s trichrome were performed. The lent@ maligna component was strongly positive for melanin. but was negative for the spindle component. No axons

BRITISH JOURNAL OF PLASTIC SURGERY

Fig. 2 Single cells and nests of atypical melanocytes present at the dermal-epidermal junction in the lentigo maligna component ( x 400).

Fig. 3 Discrete, nodular malignant spindle cell lesion without any connection with the overlying skin or transition into the lentigo maligna component ( x 40 reticulin stain).

were identified in the spindle component, but reticulin was present and tended to outline clusters and fascicles of the spindle cells, depending on the plane of section. Collagen was also present in the spindle component and paralleled the reticulin distribution.

A portion of the tumour was studied by electron microscopy. The cells were elongated and contained many profiles of rough endo-plasmic reticulum and some mitochondria. They were surrounded by collagen fibres without any basal lamina. Differentiating features such as pre-melanosomes or melanosomes were absent. heural and smooth muscle differentiation was also absent. It was considered that the elongated cells were most likely to have originated from fibroblasts (Fig. 5).

The clinical association of an overlying lentigo maligna with an apparently fibroblastic spindle cell subcutaneous lesion fulfils the accepted criteria for diagnosis of desmoplastic malignant melanoma (Conley et d.. 1971; Labrecque et nl., 1976). The failure to support a melanocytic origin of the spindle component by special stains of electron microscopy argues against this being a “spindling melanoma component” of lentigo maligna melanoma. The failure to demonstrate any other cell origin also supports the diagnosis of desmoplastic malignant melanoma and fails to support the initial diagnosis of neurofibrosarcoma.

Discussion

Desmoplastic malignant melanoma was first described by Conley and his colleagues (1971). Almost 70 ‘:, of the cases reported involve the head and neck area. These lesions arise suddenly as subcutaneous malignant spindle cell lesions and are usually associated with an overlying long-standing lentigo maligna. The case reported here is typical in every respect.

To clarify the origin of the subcutaneous nodule, special stains such as reticulin, Masson’s trichrome, Fontana melanin and Bodian stains (Conley et (II., 1971) may used. The nature of the spindle cell component has not been defined despite studies using these special stains and electron microscopy. Conley rt al., (1971) Frolow rt ~1. (1976) and Valensi (1977) have suggested a melanocytic, fibroblastic neural or histiocytic origin. Demonstration of a probable premelanosome in the spindle cells by electron microscopy in one case suggested a melanocytic origin of the spindle component (Conley et al.. 1971).

Part of the difficulty in establishing the origin of these cells lies in the interpretation of the

DI:SMOI’LASTI( MALIGNANT MELANOMA: A CASE REPORT

dcsmc)plaatic reaclion. Labrecque a tl(.. (1976) and Valensi (1977) suggest that the spindle cells are ;I reactive fibroblastic response induced by the melanoma cells rather than actual tumour cells. Similar reactive desmoplastic responses ha\~ been documented in squamous cell carcinoma and in traumatic and actinic damage (Lane. 1957; Kern, 1960: Labrecque e/ trl.. 1976).

Although the origin of the spindle cell cc~mponent has not been clearly defined. dc5moplrtstic malignant melanoma ib ;I definite clinical entity that warrants early recognition becauw of the significant clinical implications. The spindle cell component has poorly defined borders and can invade deeply (Labrecque P( rrl.. 1976). Therefore. if the entire lesion is not rcmovcd early local recurrence and widespread metasta>es will result. These metastases may contain tither a classical malignant melanoma or it pure spindle cell lesion (Conley rt oi.. 1971 ),

Because of the undifferentiated nature of the spindle cell component. careful correlation of the clinical and pathological findings is necessary to chtabliah the correct histological diagnosis.

The malignant nature of the lesion and the ;lggrescive course in the cases reported previously

(Conley c/ t/l.. 1971, Frolow c/t (il.. 1975) hupgest that early wide local excision with removal of the intervening nodes is the treatment of choice combined with a neck dissection if palp:tblc nodes are present.

References

82 BRITISH JOURNAL OF PLASTIC SURGERY

Labrecque, P. G., Hu, C. H. and Winkelmann, R. K. (1976). The Authors On the nature of desmoplastic melanoma. Cancer, 38, 1205.

Lane, N. (1957). Pseudosarcoma (polypoid sarcoma-like Daniel Man, MD.

masses) associated with squamous cell carcinoma of the L. J. Weiner, MD.

mouth, fauces and larynx. Report of ten cases. Cancer, 10, H. M. Reiman, Jr., MD

19. Valensi, Q. J. (1977). Desmoplastic malignant melanoma. A

Requests for reprints to Daniel Man, Department of Surgery, University of Louisville, 5305, Jackson Street, Louisville,

report on two additional cases. Cancer, 39, 286. Kentucky 40202, USA.