Introduction:
Leiomyosarcoma of the skin is a rare tumor that starts from the smooth muscles around the hair follicle or sweat glands. In the subcutaneous tissue, cancer emerges from smooth muscle in the arterioles and venular walls, the scrotum, the areola, or the female genitalia. It commonly presents as a nodule in the skin. As it is a rare tumor, histologic assessment is required to confirm the disease. Leiomyosarcomas are present in four clinical subtypes: intra-abdominal, subcutaneous, cutaneous, and vascular.
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Intra-abdominal tumors (40 % to 45 %) occur in older women behind the abdomen, mesentery (the membrane that attaches the intestine to the abdominal wall), or omentum (the membrane that connects the stomach with the abdomen). In addition, metastases to the lung and liver are common.
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Subcutaneous tumors (20 % to 30 %) are common in men along the extremities, primarily the thigh.
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Cutaneous tumors (15 % to 20 %) affect young men. They are painful lesions on the extremities and reappear locally.
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Vascular leiomyosarcomas (5 %) occur in older adults along the blood vessels near the walls of the muscles, chiefly the inferior vena cava of the heart and large veins of the lower legs.
What Are the Clinical Features of Leiomyosarcomas?
Leiomyosarcomas of the skin occur equally in men and women, mostly above 30 years. The common location includes the lower extremity, the thigh, the scalp, neck, forearm, and anterior abdominal wall. Some rare places are the penis and external auditory canal. The leiomyosarcomas are clinically seen as a single, smooth, firm, skin-colored nodule on the skin.
These nodules are usually fixed to the underlying structure but sometimes are depressed. The skin over the lesion may be crusted, scaly, or ulcerated. Usually, two to five nodules are randomly scattered over the body or grouped in one site. Each lesion has the same features as the solitary nodules. No spontaneous pain or tenderness on pressure is present.
When leiomyosarcoma originates within the dermis layer, it is a derivative of arrector pili muscle; while that originates within subcutaneous tissue is a derivative of small blood vessels. When the lesion is limited to the dermis, metastasis is not seen, whereas, in deeper lesions, hematogenous metastasis to the lungs is seen in 30 % to 40 % of cases.
How Is Staging Done in Leiomyosarcomas?
The American Joint Committee on Cancer (AJCC) and Musculo-Skeletal Tumor Society (MSTS) surgical staging systems are used. It involves the staging of sarcoma involving the bone and soft tissue comprising leiomyosarcoma. This staging system is classified based on the histologic grade of the lesion, its local extent, and the presence or absence of metastatic disease.
How Is Leiomyosarcoma Diagnosed?
Tests used to diagnose leiomyosarcoma include:
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A thorough physical examination with complete medical history.
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Imaging tests include X-rays, MRI (magnetic resonance imaging), CT (computed tomography), and positron emission tomography (PET).
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A biopsy is taken from the suspected site and sent for laboratory analysis. The biopsy includes core needle biopsy where tiny tubes of the lesion are obtained or surgical biopsy for a larger tissue sample.
What Are the Treatments Available for Leiomyosarcomas?
The effectiveness of the treatment depends on the size, location, and spread to other parts of the body.
Surgery:
Surgical excision of the lesion and adjacent healthy tissue surrounding it is the common treatment. When the sarcoma is very large or involves the adjacent organs, chemotherapy and radiation therapy are suggested to avoid amputation.
Radiation Therapy:
Radiation therapy implicates high-powered energy beams like X-rays and protons to treat cancer. Radiation therapy is done at three stages:
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Radiation before the surgery shrinks the tumor to make it easier for removal.
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High doses of radiation during surgery are directed at the target area without damaging the surrounding tissues.
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Radiation after surgery is aimed at killing any remaining cancer cells.
Chemotherapy:
Chemotherapy uses drugs to kill cancer cells. It can be administered orally or through an IV (intravenous) route.
Targeted Drug Therapy:
Targeted drug therapy focuses precisely on blocking the abnormalities seen within cancer cells resulting in the death of cancer cells. Targeted drug therapy is a treatment option for advanced-stage leiomyosarcoma. These are better than chemotherapy and are non-toxic.
What Other Lesions Resemble Leiomyosarcoma?
Since leiomyosarcomas appear as solitary skin nodules with no unique clinical features, a biopsy may be required to diagnose the tumor. Differential diagnosis comprises several diseases that present with nodules on the skin or subcutaneous tissue.
The other diseases similar to leiomyosarcoma are,
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Malignant peripheral nerve sheath tumor.
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Gastrointestinal stromal tumor (GIST).
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Solitary fibrous tumor.
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Desmoid fibromatosis.
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Parasitic and fungal infections.
What Is the Prognosis for Leiomyosarcomas?
The size of the tumor, mitotic rate, presence or absence of necrosis, and invasion of cancer cells into the blood vessels determine the disease's prognosis.
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95 % survival rate has been reported for tumors less than 2 cm.
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30 % survival rate for tumors greater than 5 cm.
However, the prognosis remains poor, despite applying radical therapies.
Conclusion:
Leiomyosarcoma of the skin is aggressive non-melanoma skin cancer. Subcutaneous leiomyosarcoma metastasis more frequently than dermal leiomyosarcoma. The diagnosis of leiomyosarcoma requires both clinical examination and laboratory investigation. Therefore, early diagnosis and correct surgical management are essential. Treatment involves wide resection when the lesion is confined to the dermis, irrespective of histologic grade.
