A Case of Granular Cell Tumor of the Vocal Cord

Summary

This study presents a case of a 45-year-old male with a laryngeal granular cell tumor (diagnosed via histology and staining), who was treated with plasma ablation without recurrence.

Abstract

Granular cell tumor (GCT) is a rare benign neoplasm that most commonly arises in the head and neck region. Laryngeal involvement is exceptional. A 45-year-old man presented with a 3-year history of progressive hoarseness without apparent precipitating factors. Occasional cough produced white, viscous sputum; neither dyspnea nor dysphagia was reported. Laryngoscopy revealed a smooth-surfaced, broad-based elevation involving the anterior two-thirds of the right true vocal fold. Histology revealed polygonal cells with abundant granular cytoplasm and a low nuclear-to-cytoplasmic ratio, set within a delicate fibrovascular stroma. Periodic acid-Schiff staining highlighted cytoplasmic granules. Immunohistochemistry demonstrated diffuse positivity for S-100, CD68, and neuron-specific enolase (NSE), confirming the diagnosis of GCT. The lesion was completely excised in two stages using low-temperature plasma radiofrequency ablation (LTP-RFA). At 24 months of follow-up, no evidence of recurrence was observed. GCT may be mistaken histologically for squamous cell carcinoma (SCC). Recognition of this differential diagnosis is essential for otolaryngologists.

Introduction

Granular cell tumor (GCT, Abrikossoff tumor) was first described in 1926 and popularized by Abrikossoff in 1962¹. The cytoplasm exhibits a granular appearance resulting from lysosomal aggregation, leading to the designation "granular cell tumor". Current evidence suggests a neurogenic origin, with immunohistochemical and ultrastructural findings supporting derivation from Schwann cells or their precursors². GCT can occur at any age and at any site³. Peak incidence occurs in adults aged 40-60 years⁴. The incidence of multifocal GCT in adults is 5%-16%⁵. Around 30%-50% occur in the head and neck, with 3%-10% in the larynx², and involvement of the vocal cords is extremely rare. In adults, lesions predominate in the posterior one-third of the vocal cords, whereas pediatric cases more frequently affect the anterior vocal cords and subglottis. Additional reported sites include the anterior commissure, cricoid cartilage, false vocal cords, subglottic region, and posterior cricoid area⁶.

GCT produces varied clinical manifestations and histological overlap with laryngeal carcinoma⁷, which frequently results in misdiagnosis or unnecessary extensive surgery. The present case report delineates clinical presentation, diagnostic work-up, treatment, and prognosis of vocal cord granular cell tumor, supplying clinicians with a reference to minimize misdiagnosis and overtreatment while enhancing disease recognition and management.

CASE PRESENTATION:

A 45-year-old male presented with persistent hoarseness for more than 3 years without apparent precipitating factors. Occasional cough produced white, viscous sputum; neither dyspnea nor dysphagia was reported. Past medical history included laryngopharyngeal reflux and a 20-year smoking habit of approximately twenty cigarettes per day; alcohol was consumed sporadically. No long-term medication use or family history of head and neck cancer was documented.

Evaluation at a local community hospital included two laryngoscopic examinations that revealed a right vocal cord mass requiring further assessment (Figure 1). Differential diagnoses of vocal cord cyst and vocal cord leukoplakia were proposed.

Diagnosis, Assessment, and Plan:

Rigid laryngoscopy revealed extensive thickening and protrusion of the anterior-to-mid right vocal cord; both cords remained mobile. Contrast-enhanced neck MRI (1.5 T) demonstrated mild right vocal cord thickening, normal contralateral cord, absence of surrounding-tissue invasion or bone destruction, and no cervical lymph-node enlargement (Figure 2). Chest CT excluded pulmonary metastases. Under general anesthesia, microlaryngoscopy with a suspension laryngoscope was performed. Cold-instrument palpation indicated a firm, rubbery consistency (Figure 3). Surface tissue was peeled away; deeper tissue was sampled and submitted for histology. To preserve the vocal ligament, conservative debulking with plasma-field ablation was carried out. Post-operative course remained uneventful; voice rest and inhaled corticosteroid nebulization were instituted.

Histology revealed focal mucosal hyperplasia with erosion; stromal cells displayed an elevated nuclear-to-cytoplasmic ratio and abundant granular cytoplasm (Figure 4). Immunohistochemistry demonstrated negative cytokeratin (CK) and vimentin, whereas S-100 protein (Figure 5) and neuron-specific enolase (NSE) were positive, consistent with neurogenic differentiation.CD68 positivity suggested either phagocytic capacity or a reparative phenotype. Scattered Ki-67-positive nuclei indicated low proliferative activity. Special stains showed positive Periodic Acid-Schiff (PAS) and negative Congo red. Collectively, these findings support a diagnosis of granular cell tumor.

Laryngoscopy revealed residual right vocal cord thickening 30 days postoperatively; hoarseness persisted. Microlaryngoscopy with suspension laryngoscopy was repeated 5 months later, again employing plasma ablation. Subsequent examination revealed well-healed vocal cords with complete epithelial regeneration, satisfactory glottic closure, no evidence of tumor recurrence, and marked voice improvement. Follow-up laryngoscopy at 8 months confirmed the absence of recurrence (Figure 6).

Protocol

The research protocol adheres to the guidelines of the Ethics Committee for Human Research at Hangzhou First People's Hospital. Written informed consent for participation was obtained from the patient.

1. Preoperative preparation

1. Place the patient in the supine position. Use general combined anesthesia. Perform endotracheal intubation using a cuffed endotracheal tube. The tube should be thin, with an internal diameter of 6.5 mm for male patients. Disinfect and drape the surgical area.
2. After satisfactory anesthesia, use a laryngoscope to fully expose the surgical field. Connect the laryngeal endoscope and adjust the focal length to ensure a clear image, then operate either under the monitor or directly in view.
3. Inspect the vocal cords under laryngoscopy, noting any thickening, elevation, changes in mucosal color, or irregularities in the epithelial surface.

2. Surgical procedure

1. Following resection of the epithelial layer overlying the tumor using cold instruments, obtain an intraoperative specimen of the underlying tissue for pathological evaluation. Assess tumor consistency and margins by palpating the surgical field with a blunt instrument and by comparing findings with the surrounding normal tissue.
2. Then, carry out the treatment using an LTP-RFA treatment system and other supporting surgical systems.
   1. During the operation, set the output power of the LTP-RFA therapeutic apparatus to level 3, and connect the disposable plasma cutter head to a 0.9% sodium chloride solution before turning on the switch.
   2. Use the foot pedal to control the cutter head during cutting, and use a laryngeal forceps to pull the patient's vocal cords to remove most of the tumor tissue (Figure 3).
3. Trim the edges of the vocal cord wound to be smooth, and check for no obvious bleeding. Then, after aspirating oropharyngeal secretions, withdraw the laryngoscope. Check that the patient's temporomandibular joint movement is normal.
4. Postoperatively, have the patient undergo nebulization therapy using a mixture of 5 mL of normal saline and 1 mg of budesonide suspension, with each session lasting 10 min, administered twice daily for 2 consecutive weeks to alleviate local inflammatory edema. Advise the patient to maintain vocal rest for 1 week after surgery to facilitate the healing of surgical wounds.
5. Perform the following post-operative monitoring:
   1. Oral bleeding: Within 6 h after surgery, perform visual assessment of the oral and pharyngeal mucosa as well as expectorated secretions, every 2 h, followed by assessments every 8 h thereafter. Document changes in any signs of active bleeding, such as fresh blood clots or persistent oozing.
   2. Respiration: Monitor respiratory rate and oxygen saturation (via pulse oximetry) continuously during the first 6 h postoperatively, and every 2 h thereafter to promptly detect abnormal manifestations such as tachypnea, stridor, or decreased oxygen saturation (≤95%).
   3. Swallowing function: Assess the patient's swallowing ability during water intake at 6 h postoperatively by observing swallowing movements and inquiring about subjective swallowing discomfort (e.g., pain, dysphagia). Additionally, monitor signs of aspiration (e.g., post-swallowing cough, hoarseness) within the first 3 days after surgery.
      NOTE: All materials used above are listed in the Table of Materials.

Results

In this case report, two microlaryngoscopic surgeries under suspension laryngoscopy were performed on the patient. For the first surgery, to ensure the integrity of the patient's vocal ligament, a conservative tumor resection was performed. Five months later, the second surgery was performed, during which the tumor tissue was completely removed. Pathological examination revealed the following findings: for the 'vocal cord (frozen section + routine specimen submission)', the mucosal tissue...

Discussion

GCT is characterized by slow growth and insidious symptoms⁸. The most common symptoms of laryngeal granular cell tumor are dysphonia and hoarseness, but cough, dysphagia, and odynophagia may also occur⁹. Under laryngoscopy, GCT can have various morphologies, and it is difficult to distinguish it from polyps, cysts, and malignant tumors with the naked eye. It must be confirmed by pathological examination. Differential diagnoses that should be considered include laryngeal cys...

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Disposable RF plasma scalpel head	Shenzhen Viewwall Medical Technology Co., Ltd.	VAM-Q-3830230	Sterile, ethylene oxide sterilized, disposable
Laryngeal endoscope	KARLSTORZ Germany	8714AA	Sterile,dry heat sterilized, reusable