The leiomyosarcoma that occurs on the skin includes: superficial and metastatic leiomyosarcoma. It is a malignant tumor of soft tissues, extremely rare, comprising only 4.0% to 6.5% of sarcomas.
What is Cutaneous Leiomyosarcoma?
The superficial leiomyosarcomas are subdivided into: cutaneous (SCL) and subcutaneous, depending on their location in the thickness of the skin.
They are called superficial cutaneous leiomyosarcomas when they are located mainly in the dermis and infrequently extend to subcutaneous fat; it is believed that these tumors originate in the erector muscle of the hair follicle.
The subcutaneous leiomyosarcomas are mainly found in the subcutaneous cellular tissue and originate in the smooth muscle of the blood vessels.
The superficial leiomyosarcoma is frequently found in individuals who are 40-60 years old, with a maximum incidence in the sixth decade of life. It is twice more common in men than in women.
Clinically, superficial cutaneous leiomyosarcomas often correspond to firm, solitary nodules, deeply seated, with variable erythema and hyperpigmentation, and sometimes they show ulceration due to their fixation with the epidermis, while the subcutaneous leiomyosarcomas appear as a larger mobile mass, located in hypodermis without epidermal changes; however, they do not have a distinctive clinical aspect.
Regarding its location, there is a discrepancy, while the most frequent site in the superficial cutaneous leiomyosarcomas is head and neck; the subcutaneous leiomyosarcomas are located preferably in extremities.
They are often asymptomatic (the patient does not have any symptom), but in both types there are reports of spontaneous pain, sensitivity, but also other common symptoms were: pruritus (itching), bleeding and burning sensation.
Among the predisposing factors that have been described: trauma, radiation, chemicals and sunlight are the common ones. There is no clearly demonstrated risk of transformation or differentiation of pre-existing leiomyomas in leiomyosarcomas. Although the development of various malignant tumors in scar tissue is well known, the highest association of superficial cutaneous leiomyosarcomas is found in chronic burn scars. The development of superficial cutaneous leiomyosarcomas on smallpox scars was also described.
It is important to note that the depth of these neoplasms represents the most important prognostic factor. That is, the superficial cutaneous leiomyosarcomas have a significant capacity for local invasion and subclinical extension; however, the metastatic potential of these tumors is considered to be extremely low: 5 to 10%, unlike subcutaneous leiomyosarcomas, in which local recurrence has been reported from 50% to 70% and a potential development of metastasis to distance of 30 to 60%, most commonly to lungs.
The differential diagnosis from the clinical point of view includes: cysts, lipomas, fibroids, granulomas, dermal nevus, pyogenic granuloma, neurofibromas, dermatofibromas, carcinomas, amelanotic melanoma, benign tumors derived from adnexa and other soft tissue sarcomas.
The diagnosis is made by clinical suspicion and histopathological study. Surgical excision is established as a treatment for both entities. Chemotherapy, radiation therapy and drug-directed therapy have not yet replaced surgery.
There are several factors that correlate with the prognosis, these include: tumor size, high mitotic index, presence or absence of necrosis, vascular invasion. The survival rate for tumors smaller than 2 cm was 95%, whereas in tumors that exceeded 5 cm, survival was reduced to 30%.
Recurrence is variable: 30-50% in the cutaneous form, while in the subcutaneous it reaches 70%, being this deeper and mitotically more active than the primary lesion. The period of presentation of recurrences is variable, they develop from 1 to 5 years, after surgery. It is then important to monitor patients with chest x-ray, since the highest frequency of metastases is lung, usually by subcutaneous leiomyosarcomas in a third of patients and 25% may have metastases in regional lymph nodes, which determine an unfavorable prognosis.
Cutaneous leiomyosarcomas are infrequent malignant tumors, derived from smooth muscle; they constitute 10% of soft tissue sarcomas. Its classification and prognosis depend on the place of origin and its anatomical location; 85% of the lesions occur in the extremities. The therapeutic management is always surgical, existing possibility of recurrence and metastasis, although it is rare.