INTRODUCTION: Spindle cell lipoma (SCL) is a rare, benign tumor, usually arising in the subcutaneous tissue of the shoulder and posterior neck of middle-aged and elderly men, although other unusual locations have also been reported. Only two cases of endobronchial lipomas with areas of spindle cell proliferation characteristic of SCL have been documented previously. We report the occurrence of a SCL within the trachea. To our knowledge, this is the first description of a SCL in this location.
CASE PRESENTATION: A 70-year-old man was referred to our interventional pulmonary service for management of an endotracheal tumor. The patient had been well until about 12 months earlier, when a dry cough developed. He did not seek medical attention until his cough became productive of large amounts of mucoid secretions. A thoracic radiograph was initially read as normal, but a subsequent computed tomographic scan of the thorax, obtained because of the patient's significant smoking history, revealed a 1.8 × 1.4 cm mass in the midportion of the trachea, without significant lymphadenopathy, parenchymal lung lesions, pleural or other organ involvement. The patient underwent flexible fiberoptic bronchoscopy, which revealed a mobile pedunculated lesion with smooth glistening reddish surface. The underlying tracheal mucosa appeared normal. An endobronchial biopsy was non-diagnostic. Upon referral, rigid bronchoscopy and electrocautery with a wire snare were used and successful removal of the tumor was accomplished. Gross examination revealed a pedunculated, rubbery fragment of red-tan soft tissue measuring 2.0 × 1.5 × 0.6 cm. Histological examination showed a bland spindle cell proliferation, with abundant mature adipose tissue, and focal areas of myxoid changes in association with numerous mast cells. No significant mitotic activity or cytologic atypia were seen. The overlying epithelium was unremarkable. A cartilaginous component was not identified. Immunohistochemical stains showed the lesional cells to be strongly positive for CD34, and negative for S-100 and MDM-2. From a morphological viewpoint, the diagnostic considerations included neurofibroma, hamartoma, SCL, and less likely, liposarcoma. Given the strong CD34 positivity, the lack of staining with S-100 and MDM-2, the absence of a cartilaginous component, and the presence of abundant adipocytes, a SCL was the most likely diagnosis.
DISCUSSIONS: SCL was first described by Enzinger and Harvey in 1975. It is a rare, slowly growing, usually solitary, benign variant, accounting for approximately 1.5% of lipomatous tumors. It is cured by local excision and has never been reported to metastasize. SCL are encountered most frequently in men, between the ages of 45 and 70 years, and most are androgen receptor positive. Although predominantly located in the subcutaneous tissue of the neck and upper back, and to a lesser extent in the extremities, other unusual locations such as face, oral cavity, oropharynx, parotid, orbit, breast, mediastinum, and spermatic cord have also been reported. Only one study describing four cases of endobronchial lipomas, reported spindle cell areas characteristic of SCL, though these were not tracheal lesions. Although clinically similar to simple lipomas, they are histologically characterized by the presence of CD-34 positive spindle cells with mild nuclear atypia, mature adipocytes, myxoid background, wiry collagen and numerous mast cells.
CONCLUSION: In conclusion, this is the first known case report of a SCL presenting as an obstructive lesion in the trachea. The combination of the histologic features and the immunoreactivity for CD34 favored the diagnosis. This, accompanied by prior reports, suggest that SCL can rarely present as masses in all areas of the tracheobronchial tree, from the oropharynx to the subsegmental bronchi.
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