Aggressive Nodular Fascitis of the Mandible in a Child: A Rare Case Report

Abstract

Nodular fascitis is a benign, reactive, fiboproliferative lesion that is thought to represent an over exuberant reaction to injury or inflammation. Its histological picture is very similar to fibro sarcoma. An accurate diagnosis is imperative to avoid unnecessary aggressive treatment. It occurs most commonly in upper extremities, and rarely in the maxillofacial region. We present a case of aggressive intraosseous nodular fascitis of the mandible involving the vital structures in the neck in a 10 year old boy.

Introduction

Nodular fascitis has been described in literature as a pseudo-sarcomatous lesion which is a benign, non-neoplastic proliferation of myofibroblasts, first described by Konwaler et al. in 1955 [1]. It is a rapidly proliferating, painless, firm and well circumscribed lesion arising from proliferation of fibroblasts in soft tissue. It most frequently affects the upper extremities, with nearly half the cases occurring in the upper limb, particularly the forearm, trunk and chest wall. Intra orally the buccal mucosa is the most common site of occurrence. Lesions in the tongue, floor of mouth and submandibular region have also been reported [2, 3]. In contrast, reports of maxillofacial lesions affecting the bone are few though literature cites that it usually occurs in the angle of the mandible and the symphysis and the TMJ region [3]. A phenomenon known as cranial fascitis has been described that occurs in the first year of life, eroding the outer table of skull [4]. The outer table of cranial bone is involved with the origin from the periosteum being a possibility. Its rapid growth and histopathology picture, which shows apparent infiltration of the connective tissues by a mitotically active spindle cell lesion, makes an accurate diagnosis difficult. This rare case report is of a large, aggressive lesion of nodular fascitis which is involving the mandible, extending into the parapharyngeal space and compressing the carotid space in neck in a 10-year old boy.

Case Report

A 10-year old boy was referred to the Craniofacial Unit, SDM College of Dental Sciences, Dharwad for evaluation of a swelling on the left side of mandible. History from parents revealed that the onset of swelling was 15 days with a gradual increase in size to the present dimensions at the time of consultation (Fig. 1). The child appeared healthy and there was no history of trauma or focal dental infection. On clinical examination there was a large diffuse swelling over the lower third of face extending from the angle of mouth anteriorly, to angle of mandible posteriorly. It extended into the submandibular region crossing over to the contra lateral side by a centimeter. The overlying skin showed no discoloration or pathologic changes. On palpation the swelling was firm, non fluctuant and minimally tender. Submandibular lymph nodes were palpable bilaterally. Intra oral examination revealed a pinkish grey swelling in the left retro molar trigone area with minimal obliteration of the buccal and lingual vestibules. The mixed dentition included all first permanent molars and upper and lateral incisors. There was no motor or sensory deficit on either side of the face.

Fig. 1.

Front profile showing facial asymmetry

Radiological examination of the lesion included orthopantomograph, PA view of the mandible, USG of the submandibular region, plain and contrast enhanced MRI scans. The conventional radiographs revealed a multilocular radiolucency in the left angle ramus area with a scalloped margin which indicated cortical erosion. The HRUSG of the submandibular region revealed grossly enlarged lymph nodes measuring 28 × 23 × 19 mm with loss of normal architecture. Specks of calcification were noted. No abnormal vascular flow was seen in the centre.

The MRI films (Fig. 2) revealed a well defined, predominantly homogenous, solid mass in the left masticator space. It was hypointense on T1 weighted images and mildly hyperintense on T2 weighted STIR images. Small cystic folds were seen within the tumor mass along with few vascular flow voids. The medial extent of the swelling was of concern as it was compressing the parapharyngeal space and medially displacing the left lateral oropharyngeal wall. Posteriorly it had compressed the carotid space with posterior displacement of carotid vessels. Laterally the posterior portion of left ramus and body of mandible were eroded, without demonstrable extension into the masseter. A medical evaluation complete with blood picture, chest radiograph and ultrasound of the abdomen did not reveal any abnormalities in patient’s general medical condition. There was no contributing history and patient had been apparently free of any acute or chronic ailments till the appearance of the swelling. An FNAC of the lesion carried out under local anesthesia revealed spindle cells having plump oval, elongated nuclei with moderate amount of cytoplasm. Eccentrically placed nuclei were seen in some of the cells, with a background of mixed inflammatory cell infiltrate, suggestive of nodular fascitis.

Fig. 2.

MRI showing extension of the lesion

The planned incisional biopsy procedure was performed under general anesthesia by fiber optic intubation. During the induction it was noted that the tracheal opening was found to be narrowed significantly due to pressure from the lesion which was also evident on the MRI findings. Considering that post-operative edema which was anticipated could further compromise patient’s airway, an elective tracheostomy was performed. The lesion was approached extraorally with a submandibular incision, which was well encapsulated and showed signs of vascularity. Within the capsule the tumor mass was solid, jelly like in consistency, pinkish white in color, and avascular.

The histopathology revealed loosely arranged fascicles of plump, spindle shaped cells separated by varying amounts of myxoid stroma. The cells showed eosinophilic cytoplasm with cytoplasmic extensions and vesicular nuclei. Few cells showed nucleoli and only occasional mitosis were evident the sections. The cells showed no atypia. Lymphocytes and extravasated RBCs were seen. No cartilaginous or osseous materials were seen in the sections.

Complete excision of the lesion was done after 12 days under general anesthesia with the tracheostomy tube in situ. The lesion was approached through an extended submandibular incision (Fig. 3). The lesion was well encapsulated and lobulated, extending superiorly into the infratemporal fossa. Laterally it impinged upon the ramus and angle of mandible eroding both the buccal and lingual cortical bone. The lesion was in close proximity to the submandibular gland and crossed the midline over to the contralateral submandibular region. Complete surgical excision was done and curettage of the bony eroded margins. The extent of bony erosion necessitated a segmental resection of the angle, approximately a centimeter in anteroposterior width. The mandible was reinforced with a long stainless steel miniplate using 4 mm screws. Closure was done in 2 layers with a minivac drain kept in place. At the end of surgery it was noted that there was significant reduction in pressure effect over trachea and midline shift from oropharyngeal mass. The patient was weaned from tracheostomy after 5 days and subsequent healing was uneventful. Keeping in view the rarity of the lesion the surgically excised specimen was sent to two pathology centres which confirmed the diagnosis of nodular fascitis. The follow-up radiographs showed excellent bone healing with the plate in place. Clinically there was no deviation of mandible on mouth opening. There were no signs of recurrence after 1 year of follow-up (Fig. 4). Immunohistochemistry was not recommended by the pathologist as conclusive diagnosis was reported.

Fig. 3.

Intra op photograph showing extension of lesion

Fig. 4.

Post op profile after 12 months

Discussion

The clinical presentation of nodular fascitis i.e. rapidly growing, non tender, subcutaneous diffuse swelling in head and neck region mimics malignant tumors of connective tissue especially when the incidence is in children [5]. Age incidence is reported to be during the third to fifth decades of life although it can occur at any age. Only few cases have been reported during the first decade [5]. Nodular fascitis is common in females with male to female sex predilection ratio of 1:5 [5]. They are usually found in upper extremities, trunks and rarely in head and neck region [5]. The common sites of nodular fascitis reported are in buccal mucosa, upper lip, parotid gland, master muscle, and submandibular region [5–7]. The size of the lesion reported in the literature ranges from few millimeters to a maximum of 4.7 cm. The close proximity to carotid vessels, Internal jugular vein, the medial growth causing compression of parapharyngeal space and lateral wall of oropharyngeal region which has been reported in literature makes it a rare case. Elective tracheostomy is justified since there was gross shift of midline in oropharyngeal region and the potential complications expected while working around vital structures of neck. The difficulty faced with treating a case of nodular fascitis stems from clinical features such as rapid growth, local aggressive nature and its corresponding histopathological picture. Microscopically it appears as irregularly arranged pleomorphic spindle cells in a myxoid stroma containing mild, predominantly lymphocyte infiltrate with erythrocyte extravasation [8]. At the cellular level extensive mitotic activity will be evident and interestingly absence of cellular atypia is an important feature to differentiate from sarcomas [9]. Nodular fascitis is further classified into three variants depending upon tissue of origin i.e. subcutaneous, intramuscular and fascial. The aggressive nature of the lesion has shown signs of intravascular invasion histologically [9].

Immuno histochemistry studies have been carried out but do not have a conclusive role in singling out Nodular Fascitis. The reports of lack of S100 protien mitigate against a neural lesion, and the absence of CD34 excludes dermatofibrosarcoma protuberance with reasonable certainty [6]. Immunohistochemistry is of little use as all fibroblastic lesions may stain for smooth muscle actin. Electron micrographs of the lesion have aided in identifying myofibroblasts as the cell of origin in nodular fascitis, however, a definitive diagnosis has been made on the lack of atypical mitotic figures in H&E slides [6]. In this case the clinical findings and the specific H&E slide picture provided by two pathologists helped to arrive at a definitive diagnosis of nodular fascitis. Size of the lesion is one of the differentiating factors between nodular fascitis and sarcomas of connective tissue [5]. The previous reported cases of nodular fascitis were less than 4cm in size which was considered to be diagnostic whereas in this case the lesion was large and extending into the vital structures of neck which makes it unique case. The apparent rarity and sarcomatous presentation of the lesion makes it easily susceptible to aggressive treatment. A sound diagnosis and stringent follow-up can result in successful treatment of nodular fascitis patients, following conservative surgical excision. In this particular case the extent of the lesion into the infratemporal fossa and significant cortical erosion and soft tissue compression is worth taking into account, as a warning to advocate early surgical intervention so as to avoid possible overt consequences. In conclusion this case report is an addition to the cases of Nodular fascitis reported earlier which are rare. In this case report the patient was a 10 year old male child, and the lesion was large. It diffusely extended to alveolar region of mandible superiorly, inferiorly to cricoid region, laterally it extended to sternocleidomastoid muscle and medially to midline of neck measuring 7 × 5 × 5 cm respectively. It is interesting to note that the occurrence of this large aggressive lesion in the head and neck region in a child was similar to malignant tumor of connective tissue. The other features which contribute to this rare case report are extension of the lesion into infratemporal region, parapharyngeal region, erosion of mandible and compressing over carotids. The extreme extension of the lesion and presenting in an aggressive manner through its compressive effect on the vital structures of the neck in a child makes this documentation more important. Also an accurate recognition of this lesion prevents unwarranted treatment approach.