Rare Skin Cancers

Most skin cancers are basal cell carcinomas, squamous cell carcinomas or melanomas. A small number, however, arise from other structures in the skin such as the sweat and oil glands, hair follicles, connective tissue and blood vessels. These rare skin cancers are seen far less often, which means they can be difficult to recognise and are sometimes misdiagnosed as a cyst, scar or benign lump for some time.

Because they are uncommon, treatment is guided by specialist experience and by discussion with colleagues rather than by a single standard pathway. Our surgeons see these tumours regularly in a tertiary referral setting and work closely with dermatologists, pathologists and oncologists so that each patient receives an accurate diagnosis and a treatment plan suited to their particular tumour.

• Dermatofibrosarcoma protuberans (DFSP) - a slow-growing tumour of the deeper skin that tends to spread along tissue planes and can recur if not fully removed
• Sebaceous carcinoma - a cancer of the oil glands, most often on the eyelids and face
• Cutaneous adnexal tumours - a group of uncommon cancers arising from sweat glands and hair follicles
• Atypical fibroxanthoma - a tumour usually found on sun-damaged skin of the scalp and face in older people
• Cutaneous sarcomas - cancers of the connective tissue, blood vessels or smooth muscle within the skin, including angiosarcoma and leiomyosarcoma

Each of these behaves differently, and the recommended margins, need for imaging and follow-up schedule are tailored to the specific diagnosis. Your surgeon will explain what is known about your particular tumour and how that shapes the plan.

An accurate diagnosis is the foundation of good treatment. A biopsy is taken from the lump and examined under the microscope, often with special stains that help to distinguish one rare tumour from another and from more common skin cancers. Because these tumours are unusual, the slides are frequently reviewed by a pathologist with a special interest in skin and soft tissue tumours, and a second opinion may be sought before treatment is planned.

Depending on the type of tumour, imaging such as ultrasound, MRI, CT or PET scans may be arranged to assess how deep the tumour extends and whether nearby lymph nodes or other organs are involved. Your surgeon will explain what the pathology and imaging results mean and how they shape the treatment options.

Surgery is the main treatment for most rare skin cancers. The tumour is removed by wide excision, taking a margin of normal-appearing skin and, where necessary, deeper tissue around it. The width of the margin depends on the type of tumour; some, such as dermatofibrosarcoma protuberans, require wider margins because of their tendency to extend beyond what can be seen or felt. The specimen is examined carefully to confirm that the edges are clear, and further surgery is occasionally needed if cancer cells reach the margin.

Where a wide excision leaves a wound that cannot be closed directly, reconstruction with a skin graft or local flap is planned at the same time, often in collaboration with plastic surgery colleagues, with attention to both function and appearance.

All rare skin cancers are discussed at a multidisciplinary team meeting so that surgeons, dermatologists, radiation oncologists, medical oncologists, radiologists and pathologists can review the diagnosis and agree on a treatment plan. For some tumours, radiotherapy is recommended after surgery to reduce the risk of recurrence, and for a small number of advanced cases, drug treatment through a medical oncologist may be considered.

After treatment you will be seen regularly for examination of the scar, surrounding skin and lymph nodes, with imaging arranged where appropriate. The length and frequency of follow-up depend on the type of tumour. Ongoing sun protection and routine skin checks are recommended, and you should contact the practice if you notice a new lump or change near the treated area.