Leiomyosarcomas from the mesenchymeof smooth muscle. The most common

Leiomyosarcomas are a group of rare heterogeneous malignant tumours, arising from smooth muscle mesenchyme. The tumour may arise at any site, however the uterus, gastrointestinal tract and soft tissues are the most frequently affected. Within the lung, the disease most commonly occurs as a consequence of distant metastasis, however may originate within the lung as a discrete disease entity which is exceptionally rare. We present the case of a 66-year-old gentleman who presented with dyspnoea and was found to have an incidental pulmonary nodule in which a biopsy subsequently confirmed an extremely rare primary pulmonary leiomyosarcoma. Leiomyosarcomas are a group of heterogenous tumours which arise from the mesenchymeof smooth muscle. The most common sites of origin include the uterus, gastrointestinal tract and soft tissues. In the lung, the disease most frequently arises as a consequence of distant metastasis from a primary lesion elsewhere, however it may arise as a distinct disease entity within the lung which is extremely rare. Primary pulmonary leiomyosarcoma was first described by Davidsohn et al in 1903, and accounts for less than 0.5% of all primary lung malignancies 1,2. Whilst patients may present with similar symptoms to other more commonly encountered bronchogenic tumours, many patients remain asymptomatic and are identified incidentally. Although radiological investigation plays a pivotal role in establishing the diagnosis, the findings are often non-specific with pulmonary leiomyosarcomas presenting a solitary well-defined nodules, as was the case with our patient 3. As such a definitive diagnosis can only be established by careful pathological examination of a tumour specimen combined with immunohistochemical staining to ascertain a likely site of origin. Due to the high prevalence of pulmonary nodules often detected incidentally following routine chest radiography or computerised tomography, this case thereforehighlights the importance of considering a primary pulmonary leiomyosarcoma in any patient presenting with a pulmonary nodule, particularly in those patients who enter a nodule surveillance pathway as early detection and resection has demonstrated more favourable outcomes and improved rate of survival. Leiomyosarcomas are a group of heterogeneous malignant tumours, which originate in the smooth muscle mesenchyme and most often arise within the uterus, soft tissues and gastrointestinal tract. Primary pulmonary leiomyosarcoma (PPL) of the lung is extremely rare and accounts for less than 0.5% of all malignant lung neoplasms 1.Within the lung, PPL may originate from the smooth muscle cells of the parenchyma, bronchial walls or pulmonary arteries and is classified according to the site of origin 4. The intrapulmonary type is the most common type 5.The disease typically affects middle-aged adults, with a 2.5:1 male to female predominance 6. Several risk factors have been linked to the development of PPL and include radiotherapy, chemotherapeutic agents comprising of cyclophosphamide, melphalan and nitrosoureas as well as exposure to many occupational and environmental agents including arsenic and herbicides 6.Many patients with PPL, present with symptoms similar to other commonly encounteredbronchogenic neoplasms and include persistent cough, dyspnoea, wheeze and haemoptysis alongside constitutional symptoms such as weight loss, anorexia and malaise. Alternatively, patients can remain asymptomatic or present as an incidental finding upon chest radiography, as was the case with our patient. Radiologically, the features of a PPL are often non-specific, and such lesions typically occur in the lung peripheries as smooth, solitary well-defined nodules ormasses 3. As such, in order to differentiate a PPL from a primary bronchogenic tumour an excisional biopsy is required with careful histological examination and