Management of Angiomatous Antrochoanal Polyp: Our Experience

Abstract

Antrochoanal polyps are the most common type of choanal polyp. Angiomatous polyp is a rare subtype of Antrochoanal polyp that might be misdiagnosed as malignant lesion due to its clinical features. A retrospective observational study was conducted in a tertiary care hospital in patients who were diagnosed with Angiomatous Antrochonal polyp that underwent functional endoscopic sinus surgery from 2017 to 2020. We analyzed the clinical symptoms, radiological findings, and pathological features of all patients diagnosed with Angiomatous Antrochonal polyp. Unilateral nasal obstruction, rhinorrhea, and epistaxis were the common symptoms. Antrochoanal polyps all originated from maxillary sinus and extended to nasal cavity with or without involving the nasopharynx. Expansile mass with surrounding bony destruction are typical on computed tomography imaging but specific for Angiomatous Antrochoanal polyp. The magnetic resonance revealed high signal intensity on T1-weighted images and hypo-intense rim on T2-weighted images. Computed tomography and magnetic resonance together might give rise to more accurate diagnosis of Angiomatous Antrochoanal polyp. Incisional biopsy does help if the clinician suspects a malignant lesion. Complete removal is treatment of choice for Angiomatous Antrochoanal polyp.

Introduction

Angiomatous polyp, a rare subtype of Antrochoanal polyp, is a benign and non-neoplastic lesion [1]. It is also known as angiectatic polyp and is characterized by extensive vascular proliferation and angiectasis with regions that are susceptible to vascular compromise, resulting in venous stasis, thrombosis, and infarction [2]. Its clinical and radiological features may simulate those of neoplastic lesions such as juvenile angiofibroma, inverted papilloma, hemangioma, and even malignant sinonasal tumor [3]. However, Angiomatous polyp can be treated with conservative surgical excision and recurrence is rare. Several studies discussed the findings of Angiomatous polyps on computed tomography (CT) and magnetic resonance (MR) imaging [4, 5] but there are scant reports describing the clinical features of the disease. In this study, we present a clinicopathological and radiological study of 08 patients with pathologically proven Angiomatous polyp.

Materials and Methods

A retrospective observational study was conducted in a tertiary care hospital, from 2017 to 2020. A total of 30 patients with Antrochoanal polyp were diagnosed and surgically excised by functional endoscopic sinus surgery. 8 out of 30 patients were pathologically diagnosed to have Angiomatous Antrochoanal polyp and reviewed their clinical presentation, including sex, age, symptoms and signs, sinuscopic findings, and radiologic images, including CT and MR. All patients underwent a preoperative biopsy of nasal polypoid tumor or intraoperative biopsy for frozen section, due to the high index of suspicion for neoplasia, before surgical intervention. Functional endoscopic sinus surgery to remove the angiomatous polyps and to restore optimal sinus function was performed in all cases.

Results

Clinical Features

The clinical features of 8 patients are described in Table 1. There are four females and four males. Their ages ranged from 28 to 65 years, with a mean age of 49.3 ± 12.4 years. All Angiomatous polyps were unilateral, four on the left and four on the right side, with none affecting the contralateral sinonasal cavity. The patients presented with nasal obstruction (7/8, 87.5%), rhinorrhea (6/8, 75%), or epistaxis (4/8, 50%), all unilateral. Three patients (3/8, 37.5%) had hyposmia, and one patient (1/8, 12.5%) had visual disturbance. The duration of symptoms ranged from 06 months to 3 years. Five patients had type 2 diabetes mellitus and taking oral hypoglycaemic agents. Two patients had hypertension and taking anti-hypertensive. Four patients were on Aspirin due to previous cerebro vascular accidents, three were smokers. All patients denied any history of trauma or previous surgery. All patients underwent diagnostic nasal endoscopy on their first visit and before surgery. This revealed a huge polypoid reddish to bluish mass obliterating the osteomeatal complex with a tendency to bleed on touching in five cases and a huge antrochoanal polyp extending to the nasopharynx in two cases (Fig. 1). Six patients had a diagnostic incisional biopsy of the sinonasal polyps performed on suspicion malignancy. The incisional biopsy diagnoses were blood clot (2/8, 25%), inflammatory polyp (6/8, 75%), and fibrous exudate (3/8, 37.5%). After surgery, most of the patients were free of preoperative symptoms including those with visual disturbance, however one patient still complained of smell disturbances, and one patient with nasal obstruction.

Table 1.

Clinical features of patients

Patient number	Age years	Sex	Duration of symptoms	Clinical symptoms					Laterality
				Nasal obstruction	Hyposmia	Rhinorrhea	Nasal bleed	Visual disturbance
1	52	M	6 Months	Y	Y	Y	N	N	R
2	48	F	2 Years	Y	N	N	N	N	L
3	58	F	1 Year	Y	N	Y	Y	N	L
4	64	M	3 Years	Y	Y	N	Y	N	R
5	36	F	2 Years	N	N	Y	Y	N	L
6	44	M	1 Year	Y	N	Y	N	Y	R
7	28	F	6 Months	Y	Y	Y	N	N	L
8	65	M	3 Years	Y	N	Y	Y	N	R

M Male, F female, Y yes, N no, R right, L left

Fig. 1.

Clinical photograph of Angiomatous Antrochoanal Polyp. a Nasal endoscopy revealed a huge antrochoanal polyp which bled easily when touched. b Bluish reddish necrotic gray area showing Angiomatous polyp. c Gelatinous mass with alternating dark red and gray area

Imaging Features

All patients received Non contrast CT paranasal sinus scan prior to surgery, and three patients (37.5%) had additional MRI scan on suspicion of sinonasal malignancy. On CT images, all Angiomatous ployps had the following features: origination from a unilateral maxillary sinus, involvement of the osteomeatal complex, and obliteration of the nasal cavity. Other involved anatomical sites included the Maxillary sinus (8/8, 100%), ethmoid sinus (5/8, 62.5%), sphenoid sinus (2/8, 25%), choana (2/8, 25%), and nasopharynx (1/8, 12.5%) (Table 2).

Table 2.

CT scan findings

Patient number	Tumor centre	Maxillary sinus	Ethmoid sinus	Sphenoid sinus	OMC	Nasal cavity	Posterior choana	NPX	Homogeneity
1	Rt M	Yes	No	No	Yes	Yes	No	No	Heterogeneous
2	Lt M	Yes	No	No	Yes	Yes	No	No	Heterogeneous
3	Lt M	Yes	Yes	No	Yes	Yes	No	No	Heterogeneous
4	Rt M	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Heterogeneous
5	Lt M	Yes	No	No	Yes	Yes	No	No	Heterogeneous
6	Rt M	Yes	Yes	Yes	Yes	Yes	Yes	No	Heterogeneous
7	Lt M	Yes	Yes	No	Yes	Yes	No	No	Heterogeneous
8	Rt M	Yes	Yes	No	Yes	Yes	No	No	Heterogeneous

Rt Right, Lt left, OMC Osteomeatal complex, NPX Nasopharynx

All polyps were heterogeneous in density and more masses were expansile (7/8, 87.5%) with bone remodelling and even erosion to adjacent bony structures (5/8, 62.5%) (Fig. 2). On MR images, all the Angiomatous polyps were mildly hyperintense on T1-weighted images (T1WI), heterogeneously hyperintense on T2-weighted images (T2WI), and avidly enhanced on contrast-enhanced T1WI (Fig. 3).

Fig. 2.

Axial Computed tomography PNS Scan shows shows an expansile soft-tissue mass (asterisk) centered in the right maxillary sinus with interspersed hyperdense components. The mass extended into the right nasal cavity and the right infratemporal fossa (arrow)

Fig. 3.

Axial T1-weighted Magnetic resonance image shows that a lobulated, heterogeneous mass (red arrow) with mildly hyperintense components was demonstrated in the right maxillary sinus

Pathological Findings

All 8 patients underwent incisional biopsy of the unilateral polyp before surgery on suspicion of malignancy. The findings of these biopsy procedures were blood clots, inflammatory polyps, and fibrous exudates. Post- operative specimen sent for pathological evaluation. Grossly, the submitted tissues were fragmented elastic polypoid masses. On sectioning, the cut surfaces were glittering tan with yellow–brown in colour, translucent with alternating zones of hemorrhage and edematous degeneration. They all shared similar histopathological features. The surfaces of the polyps were covered by pseudostratified respiratory-type epithelium with occasional squamous metaplasia. Beneath the epithelium there was hypocellular stroma with extravasated eosinophilic amorphous fibrin-like material with clusters of irregularly shaped and thin-walled blood vessels were seen. Areas of hemorrhage with hemorrhagic necrosis were also observed, and thrombus formation and neovascularization were found. Inflammatory infiltrate was mild except in areas of hemorrhagic necrosis and neovascularization (Fig. 4).

Fig. 4.

Histopathology photograph showing polyp covered by respiratory-type epithelium; the stroma shows marked hemorrhage and extravasation of eosinophilic fibrinoid material with with marked hemorrhage, neovascularization, and infiltration of chronic inflammatory cells. Clusters of irregularly shaped ectatic thin-walled vessels with hemorrhage and stromal fibrinoid material deposition is also seen

Discussion

Antrochoanal polyps represent 4–6% of all polyps. There are various descriptions of Angiomatous antrochonal polyps including cavernous hemangioma, hemangioma, pseudo-tumor and hemorrhage necrotic polyp. All of these polyps share the similar clinical, pathological and imaging features. In recent studies, the term “angiomatous polyp” has been suggested as being more suitable and compatible with the pathological features of extensive vascular proliferation, hemorrhage, and infarction. In our hospital, the diagnoses were also inconsistent and included inflammatory polyp with infarction and hemorrhagic or infarcted angiomatous polyp [6, 7], and we enrolled the patients according to the detailed pathological description given earlier, which shared common clinical and radiological findings.

The exact aetiopathogenesis of Angiomatous polyp is unknown. However, the presence of nasal polyps is one of the hypotheses. The polyps which usually located near the sinus ostium are subject to significant vascular compromise or infarction and leads to neovascularization and fibrosis of the polyp. Vascular stroma with marked plasma cell infiltration is a unique feature of these polyps. Several hypotheses for the pathogenesis of Angiomatous polyps have been reported in the literature. One is that it is derivative of an antrochoanal polyp [8]. An antrochoanal polyp originates from the maxillary sinus and protrudes via the sinus ostium into the nasal cavity, which may extend posteriorly to the posterior choana and even the nasopharynx. Owing to the anatomical structure, a sinonasal polyp is more vulnerable to vascular compromise or strangulation at several sites, such as at the polyp pedicle, the sinus ostium, the posterior end of the inferior turbinate, the posterior choana, or the nasopharynx [2]. Compression of the vessels results in vascular dilatation, stasis, edema, and ischemia of the polyp. This can also cause venous infarction, thrombosis formation, and subsequent neovascularization and fibrosis of the polyp [1, 9], whereupon the term “angiomatous” was proposed. This process also accounts for the progressive expansion and regional bony destruction associated with angiomatous polyp. All the Angiomatous polyps in our patients originated from the maxillary sinus, involved the osteomeatal complex, and extended into the nasal cavity, with or without involvement of the posterior choana and nasopharynx, and all featured sinus expansion and bony destruction.

Angiomatous antrochonal nasal polyps are fibrosed, vascularized nasal polyp, probably a response to a minor trauma [2]. Batsakis hypothesized that vascular compression of the polyp at the vulnerable site results in infarction followed by reparative changes and neovascularization [2]. There are four such vulnerable sites: the ostial exit site, the posterior end of the inferior turbinate, the posterior choana, and the most dependent part within the nasopharynx [3, 10].

The fragility of the AAP is due to infarction, and hence it is difficult to remove them en bloc. Perivascular pools of eosinophilic material are because of the extravasations of blood components (fibrin, platelets, etc.) through the vessels. Hence a classical histological picture is seen with thin walled vessels embedded in the eosinophilic material (congo red negative), areas of patchy necrosis, scanty inflammatory exudates (mainly the plasma cells) [11] associated with patchy necrosis and atypical stromal spindle cells (large pleomorphic) [12].

Angiomatous polyp should be differentially diagnosed from other unilateral masses in the sinonasal cavity, including inflammatory polyp, fungus ball, mucocele, inverted papilloma, and malignant tumors (such as squamous cell carcinoma, adenoid cystic carcinoma, and melanoma) [1, 4, 5]. By definition these polyps originate in the maxillary sinus, extend through the maxillary ostium and continue posteriorly toward the choanae. Lack of pterygopalatine fossa involvement despite nasopharyngeal extension is one of the hallmark features differentiating this lesion from JNA [13, 14].

Clinical, histological and radiological differential diagnosis of AAP are antrochoanal polyp, hemangioma, juvenile nasopharyngeal angiofibroma, inverted papilloma and malignancy. A suspicion of hemangioma (cavernous/capillary) may arise due to occurrences of recurrent bleeding, but this diagnosis was not supported by radiological findings. Angiomas are usually found at the anterior nasal septum, the turbinate and the vestibule [7].

Angiomatous antrochoanal nasal polyp (AAP) can easily be confused with juvenile angiofibroma [15] as the later also presents with unilateral epistaxis and nasal obstruction. By definition, these polyps originate in the maxillary sinus, extend through the maxillary ostium, and continue posteriorly toward the choanae. The main feature which differentiates AAP from juvenile angiofibroma is that the later show marked enhancement with contrast and may also extend into the pterygopalatine fossa or may have intracranial extenstion [9].

Inverted papillomas are difficult to distinguish from AAP based on clinical, radiological and often histological features. However AAP show more prominent vascular changes, which when present should alert further histological and radiological examination, enabling an accurate diagnosis to be made [16].

Another differential diagnosis is a malignancy [7]. Both the lesions show aggressive clinical behavior. Without knowledge of the typical clinical presentation and the complete study of imaging findings, the entity tends to be clinically and radiologically confused with neoplastic processes and even malignancy [9]. The mass shows minimal enhancement on the edge of the lesions. The edge of ANPs on CT is clear and does not invade the peripheral fat layer [9]. During surgery, AAP can be excised easily while malignant tumors are not that easy to excise.

All our patients denied previous surgery or history of trauma, but five patients out of eight had a history of diabetes mellitus and four were taking aspirin. Elevated blood sugar levels cause the blood vessels to be more susceptible to damage and formation of atherosclerosis. By blocking the production of prostaglandin, aspirin can dilate the vessels and prevent clotting, which may lead to haemorrhage. These conditions might have led to development of Angiomatous polyp in our patients.

The CT imaging of Angiomatous polyps were not specific [17–22]. The typical features are expansile mass in the sinus with bony wall destruction and remodeling [5]. Some other benign lesions can exhibit similar bony erosion on CT imaging, such as juvenile angiofibroma, inverted papilloma, and hemangioma [9]. Ding et al. [23] have reported that the vessel-like marked enhancement and progressive enhancement on two-phase helical CT scans are characteristic features of Angiomatous polyp, which could be a useful tool to make more confirmative diagnosis before surgery. Our patients underwent MRI to rule out malignancy. On MR imaging, slight hyperintensity on T1WI [5] and a hypointense peripheral rim around the mass on T2WI, indicative of old hemorrhage, are more specific to the correct diagnosis of Angiomatous polyp.

Limitations and Recommendations

The main limitation of the present study was low sample size, and loss of follow up after 6 months post-operative period. A high sample size and longer follow up period would elucidate more information on Clinico-pathogenesis of Angiomatous polyp.

Conclusion

Angiomatous antrochoanal polyp is a rare variant of Antrochoanal polyp. It mimics inverted papilloma, juvenile angiofibroma, and malignant tumor in its clinical and radiological aspects. The patients in our study most commonly presented with unilateral nasal obstruction, rhinorrhea, and epistaxis. The CT and MRI images showed expansile sinonasal-occupying lesions with bony destruction and obstructive sinusitis in adjacent sinus cavities. The MRI images provided more information to facilitate a correct diagnosis. There were other history findings of patients taking aspirin, were diabetic, which led to possibility of Angiomatous polyp. By definition these polyps originate in the maxillary sinus, extend through the maxillary ostium and continue posteriorly toward the choanae. Incisional biopsy pre-operatively or intra-operatively helped in confirming the diagnosis. The treatment was completely removing the polypoid mass by Functional endoscopic sinus surgery and restore sinus drainage system.

Funding

None.

Compliance with Ethical Standards

Conflict of interest

No conflict of interests.

Ethical Approval

Permission taken from the institutional ethical committee for doing this study.