GIANT MALIGNANT MELANOMA: A CASE REPORT

INTRODUCTION

Malignant melanoma, first described by John Hunter in 1787, is an aggressive melanocytic tumor arising in various sites such as skin, mucosa, central nervous system and occasionally in some other areas. Though it is accepted as a rare tumor, its frequency seems to have increased in recent years (1). The most important prognostic parameters of malignant melanoma are the size of the tumor and diameter of the ulcerated surface area (2). The case presented here is very large in size with access area of surface ulceration.

CASE PRESENTATION

A 56-year-old female patient visited our emergency department complaining of bleeding from a mass of giant size on the left thigh. The patient gave the anamnesis of a small black spot which had appeared on this region five months ago and grown rapidly without any discomfort except for occasional bleeding periods; consequently this was the first time she had consulted a physician. There was no peculiarity in the background and family history. In the physical examination, there was an 18 x 16 x 5 cm elevated, partially ulcerated, black-brown mass on the left gluteal region with active hemorrhagic areas (Fig. 1). Four enlarged, fixed, painless lymph nodes, the largest 1.5 cm diameter, were palpated in the left inguinal region. There was no peculiarity in the physical examination of other systems. Ultrasonographic examination revealed four enlarged lymph nodes in the inguinal region. In the computer tomography of the thoracic region there was more than one metastatic focus in the lungs. There was no other organ metastasis in the scanning tomography.

The mass was excised with safe surgical margins together with inguinal lymphadenectomy. The dermal defect was reconstructed by a local dermal flap and a semi-thickness dermal flap.

Representative hematoxylin-eosine stained slides were obtained from the specimen, which was fixed in 10% neutral formaldehyde and embedded into paraffin. Light microscopy revealed a tumor mass located in the dermis which was formed of epitheloid type, melanin containing cells with prominent atypia. The cells formed nests, islands and trabecula in between a network of tiny vessels. The tumor cells contained big eosinophilic nucleoli and showed prominent nuclear pleomorphism. There were a large number of mitotic figures, most of which were atypical (Fig. 2 a, b, c). The Breslow depth of the tumor, which showed a nodular pattern of growth towards the surface and which invaded the subcutaneous adipose tissue, was measured as 4.8 cm. Immunohistochemically the tumor cells showed diffuse and strong cytoplasmic positivity for S-100 protein and HMB45 (Fig. 3a, 3b). There was positive nuclear reaction for Ki67 in approximately 50% of the tumor cells (Fig. 3c). Resulting from the histopathological and immunohistochemical findings, the lesion was diagnosed as “Nodular Malignant Melanoma, Clark Level-5”. There was metastatic malignant melanoma in all of the excised lymph nodes and perinodal areas.

The patient was taken into oncologic assessment with her pathology and tomography results; however, she did not accept any recommended additional therapy for her condition, and on her insistence she was discharged from the hospital. Two months later she had to be taken to the intensive care unit with advanced disease.

DISCUSSION

Malignant melanoma, which is estimated to double its incidence in every 10-year period and to appear with 40,000 new cases every year, is becoming a real public health problem (3, 4). When the frequency rate of the tumor is taken into consideration, it occupies first place in men and second place in women after lung carcinoma (5).

Though its pathogenesis is not clear yet, sunlight exposure and genetic reasons are generally believed to be in the foreground. In particular it is thought that mutations in p16INK4, which is a gene assigned in inhibition of cyclin dependent kinases of the cell cycle, induce proliferation of melanocytes, and in course of time this causes malignant change in melanocytes (6–9).

Previous studies revealed that the most frequent localization for malignant melanoma is the face, which is followed by the trunk and the lower extremities (5, 10). In a review of the literature we have found two giant melanomas, one primary and one metastatic. The primary one was located on the sacral region with the greatest dimension of 25 cm, and the metastatic one had the greatest dimension of 35 cm in the same region (11–12). The presented case, which is localized in the left thigh with 18 cm as the biggest dimension, seems to be the second big malignant melanoma case reported in the literature. It is remarkable that in both cases the tumor site is very similar.

The main treatment of malignant melanoma is wide excision of the tumor and dissection of the lymph node sites where the tumor is drained (13). In the present case, the mass was excised with 3 cm safe margins; additionally  inguinal lymph node dissection was performed, and the whole specimen was taken for histopathologic examination.

Five-year disease free survival rate after initial diagnosis is reported as 60% in a large series of 3000 malignant melanoma cases studied by Magnus et al (14). There is no supported data showing that additional chemotherapy improves disease-free survival; however, there are some treatment protocols which advise administration of chemotherapeutic agents after surgery (2, 3). The case reported here reached its final stage within two months after her initial diagnosis and had to be hospitalized in an intensive care unit. As the post-operational period was very short, it is thought that this worse outcome cannot be due to the patient’s rejection of chemotherapy. It is believed that the most important parameters which had a major influence on the bad prognosis were the large tumor size, high Breslow depth and wide surface ulceration of the tumor, which had reached advanced stage at the time of diagnosis. The high proliferative index also seems to be one of the important parameters relating to the aggressive behavior of the tumor. 

Progression to a giant size in only five months and the immunohistochemically-determined high Ki67 proliferation index (reaching 50%) are the most important differences showing aggressive behavior when compared to other melanoma cases. In an ordinary malignant melanoma case, the expected Ki67 proliferation index should be around 20%; in the presented case it was 2.5 times higher (15). This aggressive behavior is suspected to be the main cause of rapid progression to the end stage of the disease just 7 months after its initial occurrence. This clinical behavior and the huge size of the tumor mass were felt to be of importance and to justify presenting this case.

Address for correspondence:

Kamuran Zeynep Sevin, M.D.

Sisli Etfal Research and Training Hospital Department of Plastic Surgery

Sisli Istanbul

Turkey

E-mail: kzeynep.sevim@gmail.com