Adult rhabdomyoma with oncocytic changes affecting the floor of the mouth: optical, immunohistochemical, and ultrastructural study

Rhabdomyoma of the Oral Cavity Mimicking Reactive Lesions: A Case Report and Review of the Literature

Extracardiac rhabdomyoma is a tumor that rarely occurs in head and neck region. Adult and fetal types of extracardiac rhabdomyoma are diagnosed only by histopathological examination. In the oral cavity, this lesion usually affects the mouth floor and tongue. Despite the low incidence, adult rhabdomyoma should be considered in the differential diagnosis of oral cavity lesions, and histopathological evaluation might be helpful for the final diagnosis. This study aims to report a rare case of rhabdomyoma mimicking reactive lesions and review the literature. A 34-year-old male was referred to the pathology department with a yellowish sessile lesion in the labial maxillary vestibule. During an excisional biopsy, a mass of unencapsulated soft tissue beneath the vestibular mucosa was observed. The yellowish color in clinical features has led to lipoma as the initial clinical diagnosis. The histological examination exhibited an encapsulated, well-circumscribed benign neoplasm composed of multiple lobules of large polygonal cells with prominent abundant granular eosinophilic cytoplasm. No cellular atypia was observed. Diagnosis of the adult type of rhabdomyoma was made by collective agreement. Rhabdomyoma can be mistaken for other reactive lesions and may resemble their appearance.

Adult-type rhabdomyoma of the thyroid: A case report

Adult-type rhabdomyoma (AR) is a benign myogenous neoplasm. It is rarely located in the thyroid. We present a case of a 61-year-old man, presenting with complaints of a mass found in his left neck for three years. Ultrasonography and computed tomography showed a mass in the left lobe of the thyroid. Subsequently, a fine-needle aspiration biopsy showed that the lesion was suspected to be an oncocytic neoplasm, and the patient underwent surgery. Finally, the lesion was confirmed to be an AR of the thyroid by postoperative pathological diagnosis. In conclusion, AR that occurs in the thyroid is remarkably rare. No case reports to date have described in detail the imaging findings of AR in the thyroid. This study demonstrates the imaging characteristics of a patient with AR of the thyroid, in order to provide more extensive insights to consider the differential diagnosis of thyroid lesions.

Oral Adult Rhabdomyoma

This report describes a case of an adult rhabdomyoma (ARM) occurring in the oral cavity. A 47-year-old man was referred for the diagnosis of a painless, well-circumscribed, submucous nodule located on the floor of the mouth, measuring approximately 6.0 cm in length. Computed tomography revealed a well-defined, solid, and hypodense mass. A benign salivary gland or mesenchymal tumor were the main diagnostic hypotheses. Under local anesthesia, the patient underwent surgical excision. Microscopically, the tumor comprised large polygonal well-defined cells with abundant, eosinophilic granular cytoplasm with cross striations. No atypia or mitosis was observed. The cells were positive for muscle-specific actin, desmin, and sarcomeric alpha-actin. Based on these features, a diagnosis of ARM was established. No recurrence was observed after 48 months. Although rare, ARM should be considered in the differential diagnosis of oral submucosal nodules, especially those located on the floor of the mouth.