Skin subjected to repeated thermal insults has long been recognized to have an increased incidence of carcinoma. There are two populations where a similar malignant change is common. The Indian Kangri ulcer, prevalent among the poorer classes of Kashmir, is a consequence of wearing warm embers. The Kairo burn cancer seen in Japan results from burn scars due to wearing a small tin oven underneath the clothing." However, there seems to be no predilection for particular races.' Malignant changes in burn scars may occur at any age. Seen predominantly in adults, burn scar carcinoma occurs at an average age of 53-59 yr." As a general rule the typical time lag between the burn and development of cancer is between 25 and 40 yr."'," Another interesting observation is that the latent period is inversely proportional to the patient's age at the time of the burn. The younger the patient at the time of injury, the longer the interval for malignant change, while the older the patient at the time of burning, the longer the lag period. '5 Although burn injuries are commoner in females, the majority of studies refer that males present an incidence three times greater than females."-'8 The reason for this phenomenon is unknown. Most Marjolin ulcers occur on the extremities. The anatomical locations reported by Arons," Lawrence," and Novick" show that average distribution of Marjolin ulcers is 40% in the lower extremity, 30% in the head and face, 20% in the upper extremity, and 10% in the trunk area. Several researchers have pointed out the propensity of burn scar cancer to arise in flexion creases.','' This distribution is in marked contrast to the distribution of spontaneous epidermoid carcinomas, which are located on the face and neck in more than 90% of cases. `20 In a clinical study by Hahn et a1." it was found that burns were the commonest antecedent trauma, the second commonest cause being chronic osteomyelitis. It has also been estimated that Marjolin ulcers occur in 1.5% of all osteomyelitis patients, and in 2% of all burn Victims. 1,22 One study reports an incidence of 1:1000 occurrences in patients with chronic venous stasis ulcers," Squamous cell carcinomas are by far the commonest type of cancer arising from Marjolin ulcers, with basal cell carcinomas coming second. 1,11,21 Other neoplasms have been reported arising from chronic ulcers; these include melanoma ,z5 osteogenic sarcoma," fibrosarcoma,' liposarcoma, carcinosarcoma, and carcinoma in situ.',

Pathophysiology

Treatment and prognosis

There is a measure of agreement regarding several basic principles in the treatment of Marjolin ulcers. First of all, the best treatment for burn scar cancer is preventive medicine. Once full-thickness bums occur they should be skin-grafted at the optimal moment since, generally speaking, malignant degeneration rarely develops in a primarily grafted burn. As in all wounds, infection should be addressed early. If drainage is present it should be handled appropriately. In most cases, chronic ulcers should be excised, even if they are benign, and appropriate skin grafts or flaps should be used. It has been suggested that the excisional boundaries should include 3-4 cm of surrounding normal skin tissue including muscle fascia." Kipikasa and Guzanin expressed the opinion that the excision should always be performed by cautery." This was due to their belief that surgery was the critical breaking point at which tumour cells could be washed into the bloodstream and lymphatics, leading to metastasis. This theory helps to explain the unusually high occurrence of metastasis after surgery. Amputation is now usually reserved for deep ulcerated lesions which extend into joint cavities and bone." However, some believe it should be standard treatment in all cases." Controversy continues to exist with regard to lymph node dissection. Many researchers have advocated prophylactic dissections."` However, the majority of studies recommend that lymph node dissection should be performed only when the nodes are clinically palpable.' Whatever the treatment, long-term follow-up is recommended in all cases. One study cited a 98% metastatic recurrence rate within 3 years of local excision." Most studies have indicated a recurrence rate ranging between 20 and 50%, with regional lymph nodes being the commonest sites affected, followed by the brain, liver, kidney, and lungs."" If the regional lymph nodes become involved, the 3-year survival rate decreases to 35%." Novick et al. found a 54% metastatic occurrence from Marjolin ulcers in the lower extremity." This rate was more than two times as high as the metastatic rate in any other site. Barr and Menard reported that patients with lesions in the lower extremities presented a higher rnetastasis rate and a lower 5-year survival rate than patients with lesions in any other primary site." It has been reported that patients who survive three years without metastasis have an excellent prognosis

Case report

We present the clinical case of a 32-year-old Caucasian vioman with a large, infected, and ulcerated squamous cell carcinoma mass in the parieto-occipital region who was referred to our Plastic and Reconstructive Centre. At the time of presentation, the patient presented a yellowish, keratotic, vegetative mass of hard consistency, measuring 4.5 x 4 cm. Nearby there was a deep, whitish ulcer (4 x 4 cm) invading the cranium and exposing the dura mater. Its borders were indurated and elevated. The ulcer had a foul odour and a sticky yellow exsudate (Figs. 1, 2). The chest x-ray appeared normal.The tumour was shown by CT to have invaded the cranium (Fig. 3). RMN did not reveal cervical lymphadenopathy. Other laboratory studies were found to be within normal limits. An arteriography did not show invasion of the superior sagittal sinus. Surgical resection was performed with wide margins, including the full thickness of the skull (Fig. 4). A free latissimus dorsi muscle flap measuring 19 x 29 cm was used to cover the defect (Fig. 5). No bone reconstruction was performed. One week later the flap was split-thickness grafted. The specimen confirmed the diagnosis of squamous cell carcinoma. The margins were free of neoplasm. The postoperative course was uneventful and all the surgical sites healed (Fig. 6). The patient was disease-free at six months' follow-up.
The patient had suffered a fire burn when she was 15 months old which left an alopecic scar in the parietooc;cipital scalp. She developed an unremitting ulcer two years ago that grew until she was referred to our centre. She used to hide the ulcer under her long hair. No family member knew about it until her sister glimpsed it the day before she came to us. The patient did not have clinical palpable cervical nodes. Examination of other organ systems was unrevealing. A biopsy was performed and a diagnosis was made of squamous cell carcinoma.

Fig. 1 - Pre-operative photograph of patient showing vegetative mass concealed by patient's hair. Fig. 2 - Pre-operative view of Marjolin's ulcer. Fig. 3 - CT scan showing bone destruction Fig. 4 - Intra-operative photograph of patient after total excision of tumour. Fig. 5 - Latissimus dorsi muscle used to reconstruct the scalp defect. Fig. 6 - Final result, 4 months after surgical excision of Marjolin's ulcer.

Conclusion

This paper was written in order to highlight the existence of a condition that is commoner than we may think and needs to be correctly diagnosed and treated by plastic and reconstructive surgeons. Marjolin's ulcer is not a rare phenomenon - physicians should be aware of its prevalence after burn trauma and refer cases to burns centres earlier than they usually do. The clinical signs and symptoms are often mistaken for infection, and misdiagnosis may occur. In a condition that can rapidly become devastating for the patient, clinicians must today be aware of a benign ulcer's potentiality to turn malignant. Also, prompt aggressive treatment must be initiated before metastasis occurs.

RESUME. Les Auteurs considerent le cas dune femme de 32 ans atteinte d'un epithelioma spinocellulaire etendu, infecte et ulcere daps la region parieto-occipitale. Its presentent en outre la litterature sur les patients atteints de carcinome des cicatrices de brulure.