Background: Leiomyosarcoma is one of the most common sarcomas arising in the soft tissue and somatic organs. Pleomorphic leiomyosarcoma (P-LMS) may be easily confused with a malignant fibrous histiocytoma (MFH) as both may share nonspecific morphologic features. It is reported that the larynx is the most common site for a second primary neoplasm (SPN) in a patient with a head and neck malignancy, although an SPN of the larynx following a P-LMS is extremely rare.
Case: A 57-year-old male initially underwent fine needle aspiration (FNA) of a soft tissue tumor (STS) located in the left upper arm. FNA showed the presence of clustered, large tumor cells with clear, eosinophilic and ill-defined cytoplasm and pleomorphic nuclei. A diagnosis of an undifferentiated malignant tumor was made. Histology showed the presence of MFH. This diagnosis was changed to P-LMS following a lung metastasis. A laryngeal biopsy 37 months after the initial biopsy was performed and showed squamous carcinoma. This squamous carcinoma was presumed to be an SPN.
Conclusion: This is the first case report of a patient with a P-LMS who then developed laryngeal squamous carcinoma as an SPN.