Isolated Infratemporal Fossa Desmoid Fibromatosis: A Rare Case Report and Review of Literature

Abstract

Desmoid fibromatosis (DF) arising from musculoaponeurotic structures rarely affects the head and neck region with the abdomen being the most common site of origin. These are benign tumors with locally infiltrative nature usually presenting as painless swellings that are rapidly growing. The infratemporal fossa DF is an extremely rare location with few clinical reports. This article discusses the management of a 2-year-old child with DF of the infratemporal fossa (ITF) along with literature review.

Introduction

Desmoid fibromatosis is a locally aggressive lesion arising from musculoaponeurotic structures with fibroblastic and myofibroblastic origin with no documented cases of metastases reported. It accounts for 0.03% of all neoplasms and less than 3% of all soft-tissue tumors with the abdomen being the most common site of origin [1].Head and neck sites account for 26–33% of children suffering from DF.These tumors can affect adjacent vital structures leading to symptoms such as dyspnea, dysphagia, trismus based on the location of tumor within the head and neck [2].

We present a report on a desmoid tumor arising in the infratemporal fossa (ITF) and its management in a 2 year old female patient along with a review of literature of desmoid tumors in ITF. This report highlights the uncommon site of the tumor and complexity involved in the surgical procedure. Only 5 cases of pediatric isolated infratemporal fossa desmoid tumor have been reported in literature till date [2–6].

Case Report

A 2-year old female was evaluated in the head and neck surgical oncology clinic, with a history of progressive, painless swelling of the left cheek for 7 months. There was no antecedent history of trauma, fever, trismus, weight loss or any other similar swelling elsewhere in the body. Her growth and development were appropriate for age.

Local examination revealed a diffuse, non-tender swelling measuring approximately 4 × 3 cm, bony hard in consistency with no local rise in temperature, and no local neurologic deficits. She had adequate mouth opening and no palpable cervical lymphadenopathy. Contrast magnetic resonance imaging (MRI) was obtained that demonstrated well defined T1w isointense and T2w hyperintense lesion in left infratemporal fossa measuring 4 × 4.5 × 4.8 cm (AP x TR x CC). The lesion was extending superiorly from the level of the greater wing of the sphenoid, inferiorly up to mandible, medially abutting the lateral pharyngeal wall and laterally involving the medial pterygoid muscle. (Fig. 1). She was evaluated with a trucut biopsy from the lesion and was diagnosed with desmoid fibromatosis.

Fig. 1.

Radiologic images

The case was discussed in a multidisciplinary tumor board meeting and a decision of surgical excision with combined trans-nasal endoscopic and mandibulotomy approach followed by chemotherapy was taken. The lesion was not amenable for endoscopic resection alone since it was extending inferiorly below the level of palate, which hinders access. Transnasal Endoscope was utilized to delineate the medial, superior and posterior aspect of tumor. The nasolacrimal duct was transected and ensured that the edges were everted to prevent dacryocystitis. Further, a midline lip-split incision was taken and paramedian mandibulotomy was performed after prior preplating. Mucosal incision was taken along the floor of mouth close to the mandible and extended superiorly along the anterior pillar. The tumor was medial to medial pterygoid muscle with clear planes maintained. Mandibulotomy helped in lateral and inferior dissection. Erosion of the posterolateral wall of maxilla was noted. The lingual, mental and marginal mandibular nerves were preserved. The lesion was exposed, delineated and excised en bloc (Fig. 2).

Fig. 2.

Intraoperative images

Histopathological examination of the specimen suggested a spindle cell neoplasm with tumor cells in fascicles with ovoid to elongated nuclei (Fig. 3). Immunohistochemistry showed cells that are Vimentin, Beta -Catenin—Positive, SMA—Focal positive. S100, Cytokeratin, Desmin, Myogenin were Negative and Ki 67 – 6–8% (Fig. 4) suggestive of a desmoid type of fibromatosis of the ITF. In view of recurrent nature of the tumor and difficult anatomical location, it was decided to treat her with chemotherapy. She is currently on Vinblastine (5 mg/m²/dose) and Methotrexate (30 mg/m²/dose) chemotherapy weekly and continuous oral celecoxib (8 mg/kg/day). She is planned for 26 weeks of this chemotherapy followed by reassessment.

Fig. 3.

Histopathological images

Fig.4.

Immunohistochemistry images

Discussion

Desmoid fibromatosis, also known as musculoaponeurotic fibromatosis was characterized by Stout and Lattes in 1967 [7]. Because of its locally destructive nature, the other terminology adopted for the tumor is aggressive fibromatosis. The current terminology as proposed by WHO for these lesions is clonal fibroblastic proliferation that arises in the deep soft tissues and characterized by infiltrative growth with a tendency toward local recurrence but an inability to metastasize [8].

ITF desmoids can present with symptoms of gradually progressive trismus [3] or painless swelling of the cheek. These tumors are usually isointense or mildly hyperintense on T1 weighted images, heterogeneous high signal on T2 and show enhancement following contrast administration [9]. Role of immunohistochemistry markers such as β-catenin, SMA-α, and vimentin are known to be positive and confirmatory in this tumour [10].

They are extremely rare in the head and neck. There are very few reports of the tumor involving the infratemporal fossa [2–6]. There are no isolated pediatric ITF desmoid tumors reported from India. Due to its rarity, there are no established guidelines for the management of pediatric desmoid tumors. The best evidence is from institutional review series, with a multidisciplinary modality including surgery and chemotherapy [11].

Most of the cases reported have been managed by combined modality—surgery followed by adjuvant chemotherapy. Infratemporal fossa being a difficult area to access, all of the reported cases utilized transfacial approach. Cosmetic and functional issues are inherent complications of transfacial approach in the pediatric age group. With utility of transnasal endoscopic approach, transfacial incision was avoided in our case at the same time having good exposure for dissection. With removal of the entire medial wall of maxilla, access to infratemporal fossa was obtained. Medial, posterior and superior extent of tumor was well delineated under visualization and with minimal blood loss. Due to the bulk of the tumor, access to lateral and inferior limit was not possible. Paramedian mandibulotomy approach was utilized for lateral and inferior dissection and the tumor could be excised en bloc. The lip-split incision and mandibulotomy did not have any functional implication due to preserved neurovascular structures. The child was on a normal diet by the end of 10 days.

The French sarcoma group has studied the role of chemotherapy in DF in a multi-institutional retrospective study, involving DF of extremities mainly, with 2 patients of head and neck subsite. They noted that cytotoxic chemotherapy represents an efficient therapeutic option treatment in aggressive and/or unresectable DF [12]. Devrup et al. described the role of hormonal therapy in extra abdominal desmoids with estrogen receptor-β (ER-β) expression (ER-β) [13]. The most commonly adopted regimen is the low-dose regimen of methotrexate and vinblastine [14].

The other agents used in the pediatric population include vincristine, actinomycin, etoposide, cyclophosphamide [15]. These tumors have a high propensity for local recurrence as they spread along the fascial planes, infiltrating into surrounding vital structures making the resection subtotal [16].

In our case, the patient received Vinblastine and methotrexate chemotherapy. This is based on the evidence from the results of a Pediatric Oncology group study on use of Vinblastine, methotrexate chemotherapy for desmoid fibromatosis in children. They found that this combination therapy is well tolerated and promotes tumor regression [17]. Literature also has reports of similar efficacy of this combination chemotherapy [18, 19]. Zemer et al. described their experience with desmoid tumors in the pediatric population. Their study group consisted of 17 children with desmoid fibromatosis, of whom 7 patients had the lesion in the head and neck region. They had treated the patients with surgery when resectable and treated with chemotherapy (Vinblastine, Methotrexate) when unresectable/partially resectable and achieved complete remission in all cases at follow up [11].

In the pediatric population, the role of radiation therapy is limited due to the fibrosis and growth restriction post radiotherapy. It has been suggested by Ergen et al. that radiotherapy is especially effective in recurrent disease and provides a high local control rate in the patients who received more than 54 Gy [20]

Mutations in CTNNB1 gene encoding for β‐catenin are typically noted in most desmoid fibromatosis. The three mutations in the gene identified so far are T41A, S45F, S45P of which S45P is considered a predictor for risk of recurrence [15, 21].

We also reviewed literature with focus on the desmoid tumors of ITF in the pediatric population and excluded any case series without information on the individual course of management (Table 1). We identified 5 patients on pediatric ITF desmoid tumors (age group < 1 month to 19 years) suggesting rarity of the tumor in ITF in this population. Majority of the cases were treated with surgical excision; however, no conclusion can be drawn on management guidelines due to low patient numbers.

Table 1.

Literature review of desmoid tumor in ITF in pediatric patients

Author	Year of publication	Age/sex of patient	CTNNB1 mutation	Treatment
O Ryan [4]	1987	2 year/F	NS*	Chemotherapy regimen: pulse VAC#
Sharma A [5]	2008	2 years 5 months 1 year 10 months	Positive Negative	Surgical excision Surgical excision
Ahmed S [6]	2013	19/M	NS	Surgical excision
Antonie paul [2]	2019	4 years 8 months	NS	Incomplete surgical excision

*NS not specified

#VAC vincristine/actinomycin-D/cyclophosphamide

Conclusion

Desmoid Fibromatosis of infratemporal fossa is rare and our case report highlights the surgical management of this entity in pediatric patients emphasizing on the endoscopic approach to ITF in order to avoid facial incisions in this group of patients. The importance of adding this tumor in the differential diagnosis of painless swellings and progressive trismus cannot be underestimated. An organized approach to diagnosis with histology and IHC is imperative. Although a benign lesion, management usually is multidisciplinary and customized for each patient.

Compliance with Ethical Standards

Conflict of interest

None of the authors have any conflict of interest.