An Unusual Case of Parapharyngeal Desmoid Fibromatosis - A Rare Case Report

Abstract

Desmoid fibromatosis (DF) is a rare locally aggressive, connective tissue malignancy developing in musculoaponeurotic tissues with an incidence of 2–4 per million population. We presented a case of a 3-year-old patient with a left parapharyngeal mass, histopathological examination suggesting DF, who underwent complete surgical excision without recurrence or requirement of cardiac resynchronization therapy.

Introduction

Desmoid fibromatosis (DF), also known as aggressive fibromatosis, deep fibromatosis, musculoaponeurotic fibromatosis, and desmoid tumor, is a locally aggressive, deep-seated connective tissue malignancy developing in the musculoaponeurotic tissues.[1] DF is a rare tumor in western India, with a reported incidence of 2–4 per million population, and accounts for 0.03% of all neoplasms. Since DF lacks metastatic potential, it has now been classified as “intermediate, locally aggressive” tumor in the WHO Classification of Soft Tissue Tumors but has a high propensity for recurrence. Although a vast majority of these tumors are sporadic with a presentation in 15–60 years and being more common in females, with high proclivity to develop at sites of the surgical scar, DF may also be hereditary. Familial DF develops predominantly in patients with familial adenomatosis polyposis. β-catenin pathway is believed to play a key role in the pathogenesis of DF as intracellular levels of β-catenin are regulated by the adenomatous polyposis coli (APC) gene and the Wnt pathway with genetic alterations in the APC and CTNNB1 gene, resulting in the hereditary and sporadic DF. Histopathologically, DF is characterized by heterogeneous, poorly defined, and uniform proliferation of the spindle cells that mirror myofibroblasts wrapped within a stroma of abundant collagen and a vascular network lacking capsule.[2] Consistently, there is no atypia, necrosis, or mitosis. The nuclei may contain euchromatin or heterochromatin. Studying the immunohistochemistry, DF stains are positive for nuclear B-catenin, vimentin, cyclooxygenase 2, tyrosine kinase PDGFRb, androgen receptor, and estrogen receptor but are negative for S-100, h-Caldesmon, CD34, and c-KIT. Multimodality imaging computed tomography (CT) and magnetic resonance are useful in the diagnosis, evaluation of treatment response, and surveillance of these tumors. The current initial treatment strategy for DT advocates for an active surveillance period. Active treatments in DT are multiple and include surgery, radiation therapy, systemic treatment, or a combination of these.[3]

Case Report

A 3-year-old child presented with a swelling in the left side of the neck for 2 months. The swelling was initially small in size and slow-growing and painless. The patient had complaints of difficulty in swallowing and dyspnea in the supine position but no change of voice. On clinical examination, there was a 2 cm × 2 cm firm, nontender swelling in the left submandibular region externally with diffuse oropharyngeal swelling of approximately 3 cm × 2 cm in the soft palate on the left side. No lymph nodes were palpable in the neck [Figures 1 and 2]. Cranial nerve function tests were normal, nasal endoscopy showed no mass, but indirect laryngoscopy could not be performed. The origin of the mass could be suspected to be arising from the left parapharyngeal space clinically.

Figure 1.

Clinical picture of the patient with left parapharyngeal mass with intraoperative and gross specimen of tumor

Figure 2.

Lobulated hypodense mildly enhancing soft tissue mass in the left parapharyngeal space

Fine needle aspiration cytology of the mass revealed proliferation of uniform spindle cells resembling myofibroblasts, in the background of abundant collagenous stroma. CT scan revealed a 36 mm × 50 × 60 mm lobulated hypodense mildly enhancing soft tissue mass in the left parapharyngeal space at the level of nasopharynx and oropharynx extending from pterygoid plates to hyoid bone with indentation of base of the tongue, with possible differentials being neurogenic or fibrous or mesenchymal tumor. Lesion could be seen abutting left side of the epiglottis and posterior most part of tongue, with loss of fat plane, left IJV, and ICA with focal loss of fat plane.

The patient underwent left parapharyngeal mass excision under general anesthesia. Elliptical incision was kept behind the posterior pillar of left tonsil to separate the tumor from parapharyngeal space. Dissection was carried out, and mass was dissected out from tonsillar bed. It was separated superiorly without surrounding tissue infiltration, but inferiorly, local infiltration was present in bed. Tumor was removed completely, and left tonsillectomy was done. The defect was closed primarily. Postoperative course was uneventful. The gross pathology report stated that the mass had lobulated irregular outer surface, with dimensions of 7.5 cm × 5 × 3 cm with surface membrane in certain areas and cut section of the mass showing yellowish areas of fat and hemorrhage. Microscopic examination revealed low-grade fibroblastic/myofibroblastic cells infiltrating skeletal and adipose tissue arranged in fascicles of the collagenous stroma with features, suggesting DF. The patient presented good esthetic and functional results, with no clinical and radiographic evidence of recurrence.

Discussion

Aggressive fibromatoses are distinctive lesions that are defined as a group of nonmetastazing fibrous tumors which tend to invade locally developing from the tissue of the musculoaponeurotic system with an annual occurrence of 0.2–0.4 per 100,000, with origin in the head and neck accounting for 10%–25%. In the oral cavity, DF mostly presents as a painless mass or swelling in the involved region. Among the reported cases of pediatric aggressive fibromatosis of the head and neck, 74% have underwent large surgical resection as the primary treatment modality with 16% of these tumors reporting recurrence. Wang et al. (2014) after their extensive study proposed an age-based treatment of aggressive fibromatosis of the head and neck, in which they suggested that tumors which can be resected with negative margins without functional and cosmetic impairment should undergo surgical resection as a primary treatment modality. Conservative resection has to be done with chemotherapy in patients less than 18 years of age and radiotherapy in patients more than 18 years, if the surgical resection causes impairment.[4] Our patient underwent complete surgical resection with negative margins without recurrence and is kept under active surveillance.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient (s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initial s will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.