A 48-year-old man was referred to our hospital for chronic otitis, cholesteatoma and a middle ear mass. The patient had experienced chronic otitis of the left ear from infancy and underwent surgery for cholesteatoma in the tympanum at another hospital. However, his clinical symptoms had persisted. His conscious hearing was poor, and he suffered from earache, ear boredom, headache and dizziness. The patient had no significant past medical history. The patient’s family history was unremarkable. Otoscopic examination demonstrated a large amount of pus in the left external auditory canal, a fleshy polyp present at a deeper site, and mucosal edema in the previously operated area. Audiometric assessment confirmed a severe conductive hearing loss; hearing threshold was 80 dB and auditory brainstem response was 70 dB on the affected side. Nasopharyngoscopy showed that the orifice of the left ET opened well. The laboratory examination was otherwise unremarkable. The laboratory assessment included routine blood tests. Tests for C-reactive proteins and viral hepatitis markers were negative. Glucose and serum insulin levels were normal. The unenhanced computed tomography (CT) of the temporal bone showed some changes, including a well-circumscribed, mixed density tumor with a fat density area in the ET; the lesion extended down to the left part of the tympanum and external auditory canal, without ossicular chain, which had resulted from the mastoidectomy. The T1- and T2-weighted magnetic resonance imaging (MRI) in the transverse plane showed a 3.2 cm × 1.3 cm × 2.0 cm, well-defined, homogeneous lesion with high signal intensity along the left ET. The mass showed signal intensity similar to that of the fat on all sequences and with little cartilage signal. The lesion extended down to the left part of the tympanum and external auditory canal, where the signal was slightly higher than the part in the ET. On fat-saturated T1- and T2-weighted sequences, the part of the mass in the ET demonstrated a decreased signal intensity, indicating that the mass was consistent with macroscopic fat. The mass was surrounded by a smooth, thick, hypointense capsule, which was enhanced slightly after contrast administration. The ET diameter was expanded, to about 0.8 cm. The part of the mass in the tympanum and external auditory canal was classified as a fleshy polyp. However, “hairs” were visible on the surface of the mass and cartilage surrounded by the mass could be seen in the ET area. The mass, in which the anterior lower part and posterior upper part were connected by a thin membranaceous tissue, was in the ET. It was tightly bonded to the former ET wall and could not be removed in toto, so serial partial excision was performed. The resulting cavity (composed of the tympanum and external auditory canal) was then resolved by filling with abdominal fat. On gross examination, the resected mass appeared as a cluster of irregular, soft, grey-colored tissue. Microscopically, a photomicrograph of the mass revealed characteristics of keratinized squamous epithelium, adipose, sweat gland and mature skeletal muscle tissues. Photomicrographs of the areas including the tympanum and external auditory canal revealed squamous epithelial mucosal polyps.