Cutaneous sarcomas

Introduction

Cutaneous sarcomas are generally referred to the Sarcoma unit at the Royal Marsden Hospital for management or advice, with exceptions as listed in Tertiary and joint services.
For those cutaneous sarcomas potentially treated within the Alliance, treatment guidelines are given below.

Both atypical fibroxanthoma (AFX) and pleomorphic dermal sarcoma (PDS) typically present as a rapidly growing tumour on the scalp of patients with significant UV exposure. Some nodules may be darkened by haemosiderin and mimic nodular melanoma. There is an increased incidence in patients who are immunosuppressed.
PDS and AFX lie on a continuum and distinguishing PDS relies on expert pathological assessment. Histologic features of PDS include tumour necrosis, invasion beyond superficial subcutis, or vascular/ perineural infiltration.

AFX may be managed conservatively by simple excision with a margin of normal skin, or Mohs micrographic surgery.
Local recurrence and, very rarely, nodal involvement may occur. A single six month follow up is suggested for most patients, where there is no prior schedule rendered by immunocompromise or other skin cancer.

Following the diagnostic procedure, radical surgery should be performed with an excision margin of at least 2cm.
The role of radiotherapy is not fully defined, but adjuvant treatment to 50 Gy or 60 Gy is associated with a local control rate of approximately 70%, including patients with narrow margin excision.
Follow up is tailored to the patient and may incorporate cross sectional imaging in situations of very high risk.

Further perspective on recurrence risk and follow up in AFX and PDS

A population based study of 1118 patients found the following salient facts: (a) the risk of local recurrence at five years was 10% for AFX and 17% for PDS (b) the tisk of metastasis at five years was 0.8% for AFX and 16% for PDS (c) 92% of PDS metastases occurred within three years (d) PDS metastases included both regional and distant locations, with 50% of all metastases involving lungs. Follow up recommendations were for annual clinical clinical examinations for four years without routine imaging for AFX surveillance, and for PDS, six monthly clinical review for three years followed by annual visits for at least one further year, with PETCT at all visits.
The Alliance position will remain one of tailored follow for patients who can often be elderly with significant comorbidity.

DFSP typically presents as a solowly growing, painless, ink or violet plaque on the body or limbs. It may mimic benign scarring and thus diagnosis may be delayed. Pigmented DFSP is termed a Bednar tumour.
DFSP should be excised with a margin of 2-3cm. Patients should be considered for IHC controlled Mohs surgery, or delayed complex repair.
There is an approximately 10-15% rate of distant metastasis, emphasising the importance of definitive local control.
Aggressive local recurrence or metastatic disease may be treated with radiotherapy or imatinib, but such cases should be referred to the regional Sarcoma unit.

Classic Kaposi's sarcoma typically follows an indolent course, but further lesions are liable to develop over time.
Multiple surgical excisions of small superficial lesions can provide good disease control in a proportion of patients.
For localised disease, wide field irradiation, for example using 100kV photon treatment, given as 8-10Gy single dose or 15-20Gy over one week, will provide durable control of locoregional disease in the majority of patients.
For widespread skin disease, extended field radiotherapy, chemotherapy (eg with pegylated liposomal doxorubicin) and electrochemotherapy are effective.