Low-grade fibromyxoid sarcoma in the middle ear as a rare location: a case report

Abstract

Background: Low-grade fibromyxoid sarcoma (LGFMS) is a rare soft tissue tumor with a misleadingly bland histological appearance and fully malignant behavior, typically occurring in the deep soft tissues of the proximal extremities or trunk of young adults. However, no cases of primary middle ear LGFMS have been reported previously. LGFMS is characterized by high rates of local recurrence and metastatic spread, which should be attached of great importance to clinical diagnosis and treatment.

Case description: Herein, we report an unusual case of LGFMS occurring primarily in the middle ear of a 12-year-old boy, who presented with aural fullness and gradually progressive hearing loss in the left ear for 6 months, without other related symptoms and family history. Preoperative imaging examination suggested that the lesions were located in the tympanic cavity, tympanic antrum, and mastoid portion, with equisignal or hypointense on T1 weighted image (T1WI), apparent hyperintense on T2 weighted image (T2WI), and slight enhancement on T1WI following administration of gadolinium. A decision was made to perform mastoidectomy, as the lesion was limited to the middle ear and did not invade the facial nerve canal or the inner ear. During the surgery, the mass exhibited a hard texture and smooth surface that was approximately 1.0 cm × 1.5 cm in size, not easy to bleed, and non-adherent to surrounding tissues. After consultation, a diagnosis of LGFMS was made by postoperative pathology. The patient showed an excellent recovery from surgery without any complications. At present, the patient has been followed up for 24 months, and no local recurrence or distant metastasis has been observed.

Conclusions: The primary LGFMS in the middle ear is very rare, and the clinical manifestations and related examinations lack specificity, so a clinical diagnosis of LGFMS is very difficult, and the final diagnosis is mainly determined by pathological diagnosis. Due to its malignant behavior, clinical diagnosis and treatment should be vigilant against it. Treatment of LGFMS mainly requires extensive resection combined with radiotherapy and chemotherapy if necessary, and long-term follow-up is essential. Reporting and identification of this rare case are imperative to improving our understanding of LGFMS and reducing misdiagnosis.

Keywords: Low-grade fibromyxoid sarcoma (LGFMS); case report; soft tissue tumor; the middle ear.

Figure 1

Otoscopy, audiograms, and preoperative HRCT. (A) The outcome of otoscopy in the left ear. (B) Audiograms of the patient. The air conduction results are represented by the blue “□” in the left ear and the red “○” in the right ear. The bone conduction results are represented by the blue “]” in the left ear and the red “<” in the right ear. (C) In the axial images, the red arrow represents an irregular soft tissue density mass with significant strip calcification. (D) In the coronal images, the red arrow represents a slightly rough surface of the bone in the inferior tympanic cavity. HRCT, high-resolution computed tomography.

Figure 2

Preoperative MRI. (A) T1WI, axial. (B) T2WI, axial. (C) Enhanced T1WI, coronal. The red arrow indicates the lesion site. MRI, magnetic resonance imaging; T1WI, T1 weighted image; T2WI, T2 weighted image.

Figure 3

The pathology images of the lesion. (A) Myxoid areas alternate with fibrous areas (HE, ×200). (B) Slender spindle cells with small nuclei and scant, wispy cytoplasm (HE, ×400). (C,D) The tumor cells were immunopositive for vimentin immunostaining (×200) and MUC4 immunostaining (×200). HE, hematoxylin-eosin staining.