Extensive Spindle Cell Lipoma Occupying the Retropharyngeal Space: A Case Report and Literature Review

Spindle cell lipoma (SCL) is a rare benign lipomatous tumor that typically arises in the posterior neck, upper back, and shoulders. SCL of the retropharyngeal space is exceptionally rare, with only a few cases reported in the literature. We present a case of a 32-year-old man with a 3-year history of progressive neck swelling, dysphagia, and dysphonia. The patient initially attributed the neck swelling to his heavier body habitus. After weight loss failed to resolve the mass, worsening voice quality and cosmetic concerns prompted him to seek medical attention. Computed tomography revealed a large heterogeneous mass measuring 21 cm, extending from the oropharynx to the superior mediastinum and occupying the entire retropharyngeal space. Physical examination demonstrated a diffuse, bilateral neck mass that was soft, elastic, and non-tender, with intact cranial nerve function. Transcervical en bloc excision with finger dissection was performed in collaboration with a thoracic surgeon (total operative time: 276 minutes). Histopathological examination confirmed spindle cell lipoma, characterized by bland spindle cells, mature adipocytes, and ropey collagen fibers. Immunohistochemical staining showed positivity for CD34 and S100 and negativity for desmin and MDM2, confirming the benign diagnosis. The patient became symptom-free immediately after surgery, with the most notable improvement being resolution of breathing difficulty. At 22 months of follow-up, there was no evidence of recurrence on clinical examination and contrast-enhanced computed tomography. This is the fifth reported case of retropharyngeal SCL in the English literature and the largest by size. Despite the extensive dimensions and proximity to critical neurovascular structures, simple transcervical excision with finger dissection proved fully effective. Clinicians should be aware of this rare entity and its distinction from malignant lesions such as liposarcoma to avoid overtreatment.