Inflammatory Myofibroblastic Tumor (IMT) of the Trachea Excised by Transtracheal Surgery: Case Report

Abstract

This report describes an extremely rare case of a primary inflammatory myofibroblastic tumor of the trachea. The patient underwent surgical resection by a transtracheal approach and reconstruction with esophageal tracheoplasty. This case report highlights the rarity of such tumors and a minimally invasive and safe surgical technique for tumors around the central neck structures.

Introduction

Inflammatory myofibroblastic tumors (IMTs), known as inflammatory pseudotumors, are rare and occur predominantly in the lung. Involvement of the trachea is extremely rare. ^{1 -5} This report describes an exceedingly rare case of IMT arising in the trachea. Histology and immunohistochemistry are required for the accurate diagnosis of IMTs, and surgical resection should be considered for curative treatment. ^{1 -4} The patient in this case was adequately treated by the surgery. This case demonstrates not only the rarity of this type of neoplasm but also the suitability of a minimally invasive surgical approach tumors around the trachea.

Case Report

A 22-year-old female presented with bloody sputum and stridor of 3-month duration. Chest X-ray was unremarkable. However, MRI revealed an endotracheal soft tissue lesion (Figure 1). Bronchoscopy confirmed the presence of an endotracheal lesion arising from the posterior wall of the trachea (Figure 2). The patient was transferred to our department for further treatment. Biopsy was performed under general anesthesia with tracheostomy to prevent airway symptoms due to bleeding. The histopathologic result showed spindle cell tumor, possibly with benign to low-grade malignancy.

Figure 1.

An axial and sagittal MRI with intravenous contrasts showing the tumor lesion, which indicates a soft tissue mass arising from the posterior wall of the trachea at the level of C6.

Figure 2.

Bronchoscopy showing a mass arising from the posterior wall of the trachea, causing luminal obstruction.

We performed a transtracheal procedure for the endotracheal tumor. The tumor was easily detected through the tracheostoma. The right recurrent laryngeal nerve (RLN) was identified and freed from the trachea and esophagus to avoid injury (Figure 3A). The tumor was resected with the entire posterior tracheal membrane including the right-sided tracheal cartilage (Figure 3B). The posterior defect of the trachea, measuring 2.0 cm × 1.0 cm, was reconstructed by esophageal tracheoplasty. The surgical technique was as follows: The defect was reconstructed by suturing the muscular layer of the esophageal wall and the entire tracheal wall with 4-0 monofilament absorbable suture (Figure 3C). A temporary tracheostoma was made and closed after 2 months using a hinged skin flap technique.

Figure 3.

Intraoperative findings. A, The right lobe of the thyroid gland was released from the trachea while preserving the superior thyroid artery and vein. The right recurrent laryngeal nerve is identified and secured to the entrance of the larynx to protect it. B, A vertical Incision is made in the first tracheal ring and the tumor is well confirmed from the tracheostoma. The dotted line is the resection line. C, The posterior wall of the trachea was reconstructed by esophageal tracheoplasty. The muscular layer of the esophageal wall and the entire tracheal wall were sutured with 4-0 monofilament absorbable suture.

Histologically, oval to spindle-shaped tumor cells densely infiltrated throughout the tracheal wall; tumor cells were seen from just below the tracheal mucosa and surrounded the bronchial cartilage and glands. The tumor cells lacked polymorphism and with few mitotic figures. They grew in a storiform pattern accompanied by stromal hemorrhage and mild-to-moderate lymphocytic infiltration, sometimes with foam cells and Touton-type giant cells (Figure 4A-C).

Figure 4.

A, Dense infiltration of tumor cells surrounding infiltrated the tracheal cartilage and glands was seen (H&E, ×12.5). B, Oval to spindle-shaped tumor cells grew densely in a storiform pattern, accompanied with lymphocytic infiltrate (HE, ×100). C, Stromal hemorrhage and infiltration of foam cell and Touton-type giant cells (arrow head) are sometimes seen (H&E, ×100). D, Immunohistochemistry for ALK showed strongly and diffusely positive except for vascular endothelia and Touton-type giant cells (arrow head; ALK-IHC, ×100). ALK indicates anaplastic lymphoma kinase. IHC indicates immunohistochemistry.

Immunohistochemical analysis for tumor portion showed positive for anaplastic lymphoma kinase (ALK; Figure 4D), S-100, CD1a, CD68, CD31, β-catenin (cytoplasmic), MIC2/CD99 (cytoplasmic), and negative for smooth muscle actin (SMA). The MIB-1 labeling index was 3%. The fluorescence in situ hybridization (FISH) for EWSR1 (Ewing sarcoma breakpoint region 1) and ALK showed ALK gene split in tumor cells. The final pathological diagnosis of IMT arising from the trachea was given. After the surgery, the symptoms resolved and remained without any evidence of recurrence 3 years after the procedure.

Discussion

The nature and etiology of IMT is controversial. The global prevalence is considered to range from 0.04% to 0.7%, and the most frequent site of origin is the lung. Tracheal or laryngeal involvement is exceedingly rare. ^3,4 The clinical symptoms of IMT are nonspecific and vary depending on the location. Patients are usually asymptomatic in the early stage of tracheal IMT; however, hemoptysis or wheezing may become apparent as the tumor grows. Therefore, tracheal IMT is often diagnosed and treated as asthma or other inflammatory lung diseases.

The diagnostic protocol includes radiographic methods (eg, CT and MRI), which can reveal a mass lesion, and bronchoscopy, which can show an intraluminal polypoid tumor with a smooth surface. The definitive diagnosis is based on histopathological and immunohistochemical evaluation. When performing a biopsy, extreme care must be taken for the possibility of bleeding, which can be a life-threatening emergency, as with other subglottic or tracheal tumors. Here, a bronchoscopy performed by the previous physician revealed that the tumor was easy-to-bleed tumor. Therefore, biopsy was performed after the tracheostomy.

Histologically, IMTs have 3 basic patterns: (a) a myxoid/vascular pattern with spindle or stellate myofibroblasts in an abundant myxoid stroma with an inflammatory component; (b) compact spindle cells that may form a storiform pattern intermingled with inflammatory cells; and (c) dense plate-like collagen with low cellularity and, rarely, inflammatory cell stroma. ^{6 -8}  The present case composed mainly of pattern (b) and occasionally of pattern. Although some of the present immunohistochemical results were confusing, such as SMA-negativity and partial S100-positivity, immunohistochemistry for ALK as well as FISH analysis for the ALK gene split brought us to the correct diagnosis of IMT. Since S100-positive cells were also immunopositive for CD1a in the present case, these cells were considered to be infiltrated dendritic cells, rather than tumor cells. It also merits attention to know that SMT reactivity varies in IMT.

Inflammatory myofibroblastic tumor was originally described as a benign, nonneoplastic proliferative lesion that could be treated with conservative surgery. ¹ There is also a report that steroid hormone administration is useful as a postoperative adjuvant therapy. ¹ Surgical resection is recommended for tracheal IMT causing luminal compromise. Like other primary tracheal tumors, sleeve resection of the trachea may often be considered. However, the problem with this procedure is that strict postoperative neck rest is required, and if tracheal anastomotic leak occurs, a fatal infection can result. Other treatment modalities such as endoscopic removal with CO₂ laser or electrocautery are minimally invasive treatments, ^1,9 but en bloc resection with a safe surgical margin might be difficult because of the limited working space. Furthermore, there is a risk of mediastinal emphysema and mediastinitis if the entire tracheal wall is removed. Intraoperative or postoperative bleeding can flow into the bronchi and be fatal. We applied transtracheal surgery for this case, and the tumor was safely removed without severe complications.

We previously reported the feasibility of transtracheal dissection for metastasis of thyroid gland cancer. ¹⁰ This surgical technique enables us to identify the tumor site with ease and without damaging the RLN. There is less risk of infection without strict postoperative neck rest. The disadvantage of this procedure includes the need for a temporary tracheostomy which can be closed under local anesthesia after about 1 month.

Esophageal tracheoplasty, which we used for this case, has been used for pediatric tracheal stenosis. ^9,11,12 This procedure is selected when the esophageal wall is otherwise normal with only a defect in the posterior wall of the trachea. ¹² It was considered useful as a simple and safe surgical procedure.

In conclusion, IMT is a rare tumor arising in the airway. A correct diagnosis by safe and secure biopsy is necessary for effective treatment with surgical removal. The procedure of transtracheal resection and esophageal tracheoplasty for a tumor involving the trachea and esophagus was safe and effective.