Lipomas are rarely observed in a subpleural localization. Clinical signs are uncommon and most are an incidental discovery at x-ray. We report a case of an incidentally discovered lipoma in the subpleural area observed in a 56-year-old patient. Physical examination showed normal respiratory function. An extrapulmonary intrathoracic opacity situated in the right axillary area was observed on standard chest x-ray. Computed tomography established the diagnosis of a subpleural fatty mass. This case draws attention to this uncommon localization of lipomas and illustrates the contribution of computed tomography for diagnosis. The CT pattern allowed us to avoid transmural or surgical biopsy.