Primary malignant melanoma of the lung: a case report and review of the literature.

Melanomas of the respiratory tract are usually metastatic in origin, and finding a primary melanoma is very rare. We report the case of a 60-year-old man who presented with a 2-month history of cough with associated weight loss. The histopathologic findings were consistent with those of a melanoma. Before considering the diagnosis of primary melanoma of the lung, an extensive diagnostic workup was done to rule out metastasis from an occult primary tumor. In addition, previously reported cases of primary lung melanoma were reviewed, and the established criteria for determining the primary site were applied. Because the precise etiology has not yet been elucidated, the possible mechanism is discussed.