Angiofibrolipoma of the soft palate: a very rare cause of upper air way obstruction in an infant

Introduction: Infants and children are very prone to air way obstruction due to smaller and immature air ways. There are multiple causes of upper airway obstruction in infants like infections, congenital lesions and rarely tumours of the upper airway. However, angiofibrolipoma, a rare variant of lipoma causing intermittent respiratory distress in an infant has not been reported until now. Objective: To report a very rare case of angiofibrolipoma arising from the soft palate in an infant. Case report: Two and half months old female child reported to the department of otolaryngology with a history of intermittent airway obstruction since one month of age. After evaluation she was found to have a fleshy polypoidal mass above the laryngeal inlet arising from soft palate causing airway compromise. She underwent surgical excison with bipolar cautery under general anaesthesia. Conclusions: Few cases of angiofibrolipoma has been reported in adults but none has been reported in children. This is to report a case of angiofibrolipoma in child causing airway obstruction.


INTRODUCTION
Airway obstruction in an infant can be catastrophic and it is imperative that an experienced team is involved in the management at the very earliest. There are several causes of upper air way obstruction in an infant from congenital conditions like laryngomalacia, laryngeal web and well established benign tumours like hairy polys. Angiofibroma causing upper airways obstruction is very rare that no cases have been reported in an infant so far.
Angiofibromas, a rare histopathological variant of lipoma is characterized by mature adipocytes, blood vessels and dense fibrous collagenous tissue. Lipomas are among the most common mesenchymal neoplasms, the head and neck regions are affected in 15% to 20% of cases and only 1% to 4% of these tumors are located in the oropharynx [1][2][3] . The most affected anatomical sites in the oral cavity are the buccal mucosa, lips and tongue. The floor of the mouth, palate, retromolar pad and salivary glands are involved less frequently 1,4 . They are usually seen in an adult after the age of 40 years and seldom reported in children and very rarely in an infant [5][6] . They can be sesile or pedunculated depending on the site of origin. When it involves mobile structures like soft palate and larynx, they tend to be pedunculated as they are in constant motion during deglutition, respiration and phonation [7][8] . When it involes the air way, the severity of symptom depends upon the location and size of the tumour. The diagnosis of an angiofibrolipoma is a histological diagnosis and is the rarest variant of lipoma 5,7,8 .
Literature search revealed a total of three cases of intraoral angiofibrolipomas (tonsil, buccal mucosa and retromolar region), one case in the larynx and ear canal each. The following case is an angiofibrolipoma arising from the soft palate in an infant causing intermittent airway obstruction.

CASE PRESENTATION
A two and half months old female infant was seen by paediatrician due to intermittent respiratory distress since one month of age, which was relieved by turning the baby to prone position. Suspecting a case of laryngomalacia, she was referred to the department of otolaryngology for further evaluation. However, the mother gave a history of respiratory distress especially during breastfeeding which results in vomiting. On vomiting, respiratory distress settles and baby starts breathing normally. On two occasions she saw a grape sized lump in the baby's oral cavity. The baby also developed apnoeic spells at night which improved when she was kept in a left lateral position.
On admission to our department, baby weighed 5.2 kg and was breathing normally without any distress or stridor. The baby was afebrile and oral cavity examination revealed normal  She had normal heart sounds. No other congenital deformities were noted. Her cry was also normal. Fibre optic nasopharyngolaryngoscopy was done via the right nostril and it revealed a fleshy, grape size pedunculated mass over the laryngeal inlet as shown in Figure 1. The site of origin could not be ascertained as the infant was crying. It was assumed that the most likely origin of the mass must be from the vallecula. However, Epiglottis, vocal cords and hypopharynx were found normal. A diagnosis of pedunculated vallecular mass was made and excision under general anaesthesia was planned.
Complete blood count was normal and chest X-ray showed normal lung fields. 2-D echocardiogram was requested by anaesthetist to exclude any congenital heart conditions.
Since the infant was not cooperative, 2-D echocardiogram was performed under sedation, which was found to be normal. In the Echo room baby developed severe respiratory distress and cardiac arrest. Cardiopulmunary resusscitation was performed followed by intubation and baby was kept on ventilation. After obtaining a high risk consent from parents, she was taken for excision to the operation theatre.
During the surgery, no mass or any lesion was found in the orpharynx, larynx or hypopharynx. It was assumed that the mass underwent traumatic amputation during emergency intubation. Intra operative fibreoptic nasolaryngoscopy was done and the mass was found lying near the left choana in the nasopharynx. It was pushed to the oropharynx and delivered to the oral caivty. The fleshy tumour was found arising from the superior surface of the soft palate on its left side near the edge.
The mass was excised using bipolar cautery and sent for histopathological examination as shown in Figure 2. A prolonged slow recovery from anesthesia was done and was able to extubate as the baby had strong respiratory effort. The baby was kept in high dependency unit for 48 hours and then in the postoperative ward for 72 hours.
Histopathology revealed poylpoid piece lined by squamous epithelium with underlying stroma composed of fibrous tissue with mature adipose tissue admixed with dilated vascular channels as shown in Figure 3 and 4. At six months follow up, the baby girl was active and growing well with no complaints of respiratory distress. Fibreoptic nasopharyngolaryngoscopy did not reveal any recurrent lesion.

DISCUSSION
Lipomas are called as universal tumour or ubiquitous tumour as it is the commonest tumour arsing from the mesenchyme 9 . They mainly occur from the subcutaneous tissue in the neck, back, abdomen, armpit and face. ipomas are rarely found in the oral cavity.
Lipoma constitutes about 0.5-4.4% of all benign mesenchymal neoplasms of the oral cavity 1-3 . The buccal mucosa is the most common site, followed by the tongue, floor of mouth, lips and gingiva 1-2 . Roux reported the first case of lipomas in the oral cavity in 1848 which was found in the alveolus termed as yellow Epulis 10 . Lipomas affecting the oral cavity are found in adults with the mean age of 50 years 1-3 . It is very rarely reported in children.
Lipomas can be histologically classified into different types depending on the admixture of mesenchymal elements such as fibrolipomas, fibromyolipomas, osteolipoma, intramuscular lipoma, angiolipoma, salivary gland lipoma, spindle cell/ pleomorphic lipoma, chondrolipoma or myxoid lipoma 1,2,4,6,8 . Lipomas and fibrolipomas account for approximately 80% of all lipomas, followed by intramuscular lipomas and spindle cell lipomas 1,2,12 . One of the rarest of the variants is angiofibropilopma which was initially grouped under harmatoma 11 . Kershisnik et al in 1986, described the first case of angiofibrolipomas which contained fat cells, blood vessels, and connective tissue 12 .
The Sign and symptoms of angiofibrolipomas will depend on the size and site of the lesion. In this case, it was a pedunculated mass about 2.5 cm in size with a fleshy stalk of about 5 cm. From clinical presentation and macroscopic appearance, the mass looked like hairy polyp but the histology proved it otherwise. Hairy polyps are rare but well established cause of neonatal and infantile air way obstruction [13][14][15] .
Since the respiratory distress started from the age of one, it could be a congenital lesion which grew big enough to obstruct the airway by two and half months time. However, it remains to be proven as there is no literature on congenital lipomas in oral caivity and palate because of its pedunculated nature, it fell down into the larynx when the baby was feeding and sleeping, thus causing respiratory distress. On turning the baby to prone position and during vomiting, the mass was pushed back to the oral cavity or nasophayrnx thus opening the airway and relieving the distress. When the infant was turned towards the left lateral positin on sleeping, the mass was lying in the valleculae or pyriform fossa thus not obstructing the laryngeal inlet.
During sedation of baby for the echocardiogram, the baby underwent deep sedation which caused the loss of pharangeal muscle tone and the mass dropped down into the laryngeal inlet causing complete obstruction. Turning the baby to prone position couldn't relieve the obstruction becasue the muscle tone of the phaynx was lost or minimal due to sedation. Thus the baby underwent cardiac arrest due to hypoxia. Therefore in such cases where there is a pedunculated lesion causing intermittent airway obstruction like the case described here or in hairy poylps, any forms of sedation should be a contraindication as it can cause catastrophic airway obstruction leading to death.
The aetiology of lipomas remains elusive till date [1][2][3]11,12 . Different theories of differentiation of multi-potent mesenchymal cells in fat tissue, cartilage and bone, to metaplasia of a preexisting lipoma are described 2 . The most widely acknowledged theory for the pathogenesis of lipoma is the "metaplastic theory" which postulates that lipomatous proliferation occurs due to the anomalous differentiation of in situ mesenchymal cells into lipoblasts, as adipose tissue can be derived from mutable connective tissue cells at more or less any topographic location in the body 1,2,16 . Being the rarest of the variants of lipoma, angifibrolipoma consist of mature adipocytes with fibrous tisssue admixed with dilated vascular channels as shown in the Figures 3  and 4.
In literature there are few case reports of angiofibrolipomas being reported in the oral cavity and pharynx. A case of angiofibrolipoma of the buccal mucosa was in a 59 years old female by Brkick et al in 2010 6 . Another case of angiofibrolipoa involving the retromolar pad region was reported by Hosseini et al in 2014 5 . Bochnia et al. reported a case of pedunculated angiofibroma of the larynx causing dysphagia in a 68 year old man 8 . All the reported cases of angifibrolipomas were in the adult population. This is the first case of angifbrolipoma being reported in an infant to the best of my knowledge.
Surgical excision is the treatment of choice for lipomas and pedunculated lesions are easy to excise 1-3 . Recurrence after surgical excisions are very rare for oropharangeal lipomas as compared to the deep lipomas which have a recurrence rate of 30% to 50%, probably because of the difficulty of complete surgical removal 1,3,12 .

CONCLUSIONS
This paper reports an extremely rare case of angiofibrolipoma arising from the soft palate causing airway obstruction in a two and half month old infant. Literature review until now shows this is the first of such case to be reported.