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Leiomyosarcoma: Rare soft tissue tumor could have grave repercussions if diagnosis is missed


Leiomyosarcoma (LMS) is a very rare soft tissue tumor; however, if the diagnosis is missed, repercussions can be grave, reflected in a poor prognosis. Clinicians should be aware of the cutaneous variant and, although LMS is rare, it should be considered in the differential diagnosis of obscure and ambiguous presenting tumors.

Key Points

Buenos Aires, Argentina - Because of the rarity of leiomyosarcoma (LMS), its confirmed diagnosis in a patient can initially surprise even the most experienced dermatologist, and the rare soft tissue tumor has the potential of a very dismal prognosis.

Therefore, making an accurate and timely diagnosis of LMS is crucial for a more favorable prognosis for the patient.

Diagnosing leiomyosarcoma

"Accurately diagnosing a leiomyosarcoma, especially the cutaneous manifestation of the lesion, is very challenging, because most physicians have very little, if any, exposure with this soft tissue tumor, simply because leiomyosarcomas are so incredibly rare.

"The clinical aspects of the tumor are, therefore, noncharacteristic and nonspecific, often leaving the clinician uneasy and unsure about the exact diagnosis," says Mario Marini, M.D., Ph.D., chief of the department of dermatology, British Hospital, Buenos Aires, Argentina.

Case study

Dr. Marini recently reported on a case study in which a 73-year-old male Caucasian patient presented with a 2 cm diameter, pink, firm, mobile, non-ulcerated tumor on the medial thigh region, characterized by a burning sensation, which had slowly progressed in size over a three-year period. The patient was in good health and had no palpable lymph nodes upon physical examination.

The possible diagnoses of the tumor that Dr. Marini and his staff considered based on clinical examination included fibrohistiocytoma, fibrosarcoma, leiomyosarcoma or a metastasis.

The lesion was excised with broad margins, and histopathology revealed a tumor synonymous with leiomyosarcoma, showing smooth muscle spindle cells in a fascicular pattern occupying most of the reticular and papillary dermis, as well as atypical nuclei and a high mitotic rate, also dominating the histological picture.

Immunohistochemical examinations were positive for smooth muscle's vimentin and actin.

Importance of case

"The importance of this case is to be able to carry out a correct differential diagnosis between the different clinical and histological varieties of superficial leiomyosarcomas. It is important to remember that the cutaneous form of leiomyosarcomas almost never metastasize; however, they are associated with local recurrence in approximately 30 to 50 percent of cases.

"This is in stark contrast to the subcutaneous form of LMS that often metastasize - commonly to the lung - and subsequently, have a high mortality rate, ranging between 30 and 50 percent of cases," Dr. Marini tells Dermatology Times.

Leiomyosarcomas represent approximately 5 percent to 10 percent of all soft tissue sarcomas. The superficial form of LMS corresponds to a group within these neoplasias having a lower incidence of approximately only 2 percent to 3 percent, which usually have a better prognosis due to the superficial location.


The current literature does not specify the follow-up protocol for these patients; however, Dr. Marini believes that patients with leiomyosarcomas should be followed up once a year for at least five years.

According to Dr. Marini, this patient was considered lucky because of the superficial location of the tumor, combined with the quick and effective treatment he received. Fortunately, after the first year of follow-up, the patient did not have any local recurrences or systemic spread of the tumor, confirmed by a referral to an oncologist.

"Recognizing this tumor early is important in a favorable prognosis for the patient. It is crucial to make the distinction between the cutaneous and subcutaneous forms of this tumor in order to give an early and proper prognosis, and provide an accurate and effective treatment to the patient," Dr. Marini says.

Disclosure: Dr. Marini reports no relevant financial disclosures.

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