Olfactory Neuroblastoma: A Novel Site of Presentation

Abstract

Olfactory neuroblastoma (ONB) or esthesioneuroblastoma is a rare malignant intranasal tumor, commonly originated from upper part of nasal cavity. Majority of cases presented with nasal obstruction or epistaxis. ONB is rarely reported in ectopic locations. Here we present the first-ever documented case of an olfactory neuroblastoma situated anterior to body of maxilla, presented as left sided facial swelling. This case report is aimed at achieving the consideration of this rare tumour as a differential diagnosis in the lesions of the anatomical region surrounding the commonly known site of origin i.e. the sinonasal cavity.

Introduction

Tumours involving the sinonasal cavity are considered rare entities. On the top of that, a wide variety of tissues of origin make them histologically very variable making the incidence of one particular type very low. Originally described by Berger and Luc in 1924, olfactory neuroblastoma (ONB) or esthesioneuroblastoma is a malignant sinonasal tumour. It accounts for only 3% of intranasal tumours. It may present in the form of nasal obstruction (70%), epistaxis (40%), headache, nausea, cervical lymphadenopathy or facial swelling [1]. Such relatively innocuous symptoms often lead to a significant delay in the diagnosis [2]. It shows bimodal age distribution with peaks in the second and fifth decades of life [3].

Usually originating from the upper nasal cavity, the tumour may show variable extension into the ethmoid sinuses, orbit, and anterior skull base [1]. In certain cases, however, the tumour may show an ectopic site of origin [2]. Here we present the first-ever documented case of an olfactory neuroblastoma (ONB) situated anterior to body of maxilla. This case report is aimed at achieving the consideration of this rare tumour as a differential diagnosis in the lesions of the anatomical region surrounding the commonly known site of origin i.e. the sinonasal cavity.

Case Report

A 20-year-old female patient presented in our outpatient department with complaints of a swelling on left cheek close to the nose for the last 3 months and left sided nasal obstruction for the last 1 month. The swelling was gradually progressive in size and the obstruction worsened with every passing day. Examination revealed a 2*3 cm firm to hard swelling lateral to left ala of the nose. It was globular and non-tender; the overlying skin was free butthe swelling was fixed to the underlying structures. On anterior rhinoscopy, a bulge on left lateral wall of the nose was observed in the anteroinferior part. Rest of the examination of the nose, nasopharynx and neck did not reveal any significant findings. The Computed Tomography scan of the nose and the paranasal sinuses showed a left-sided ill-defined soft tissue density lesion (34*28*19 mm) anterior to the body of maxilla extending along lateral wall of left nasal cavity. [Fig. 1].

Fig. 1.

Computed tomographyy axial scan PNS (pre-operative) showing soft tissue density lesion at left premaxillary area

After obtaining the written informed consent, the patient was posted for surgery.Excision of the lesion was performed by sub-labial approach. The mass was found adhered to anterior surface of the maxilla. In-toto removal of the mass was done and the specimen sent for histopathological analysis.

The HPE report was suggestive of poorly differentiated malignant neoplasm. Immunohistochemistry (IHC) was performed thereafter which was suggestive of malignant neuroectodermal tumour, most consistent with high-grade ONB (Hyam’s grade 4).

[HISTOPATHOLOGY: MICROSCOPY: Section show malignant tumor composed of nests of ovoid cells with high N:C ratio, nuclear enlargement of stippled chromatin. Foci of fibrosis and necrosis seen ( Fig. 2).

Fig. 2.

Histopathological image of olfactory neuroblastoma

Immunohistochemistry (IHC): PAN CK—Negative; EMA—Negative; Vimentine—Positive; Ki67 index—40–50%; Synaptophysine—Positive; S 100—Negative; Chomogranin—Negativ; CD 56—Positive; CD 99—Negative; Desmin -Negative.

Diagnosis: Malignant neuroectodermal tumor, most consistent with high grade olfactory neuroblastoma (grade 4)].

The patient was subjected to adjuvant radiotherapy. On follow-up at 3 and 6 months post operatively, there was no recurrence of signs or symptoms. Post-operative CT nose-PNS at the 6-month follow up showed no disease recidivism.

Discussion

The low incidence of sinonasal malignancies makes research in this field a challenging task, particularly for ONB. Consequently, there are several controversies surrounding the topic. One such area being the cell of origin for the entity under question. Though usually said to arise from olfactory neuroepithelium in the olfactory rim of the nasal cavity, ONB may sometimes present in areas that completely lack this tissue. The documented ectopic sites for ONB include but are not limited to the sellar region, sphenoid sinus, maxillary sinus, floor of nose, inferior meatus and the nasopharynx [2] (Table 1). Hence the ectopic presentations remain unaccounted for. Some of the potential emerging candidates are ectopic cell rests, Jacobson's organ, persistent terminal ganglion cells, and sympathetic/parasympathetic autonomic ganglia in the sinuses.The premaxillary area has never-before been mentioned as a site of origin for the tumour.

Table 1.

Various reported ectopic sites of olfactory neuroblastoma (ONB)

Sr. no.	Study	Ectopic Sites (No. of Cases)
1	Wormald et al. [1]	Sphenoid (1) Anterior ethmoid (1) Nasopharynx (1) Floor of nose (1)
2	Chacko et al. [4]	Sphenoid/petrous apex (1)
3	Lee et al. [5]	Inferior meatus of nose (1)
4	Mariani et al. [6]	Pituitary gland (1)
5	Meshberg et al. [7]	Maxillary sinus (1)
6	Morris et al. [8]	Sphenoid (1)
7	Purohit et al. [9]	Sphenoid (1)
8	Castro et al. [10]	Nasopharynx (1)
9	Roy et al. [11]	Pituitary gland (1)
10	Sajko et al. [12]	Sellar region (1)
11	Sarwar [13]	Sellar region (1)
12	Sharma et al. [14]	Sphenoid (1)
13	Zappia et al. [15]	Maxillary sinus (1)
14	Holmes et al. [16]	Maxillary sinus (1)
15	Present study	Anterior to body of maxilla-Premaxillary (1)

Ectopic ONBs may resemble other infective/inflammatory/benign/malignant pathologies occurring at the same site. Hence, an accurate diagnosis would demand a significant index of suspicion in the first place. This highlights the importance of a careful evaluation of morphology of the lesion and correlation with the clinical presentation. IHC marker studies are an important aid in assisting the diagnosis and critical for exclusion of other entities [2].

Once correctly diagnosed, the tumour is graded for the prediction of its subsequent clinical behaviour. One of the popular grading systems is the Hyam’s grading system, which takes into account the maturation spectrum of the tumour [1]. Its has been mentioned to carry significance in terms of prediction of survival, resectability of tumour, selection of patients for adjuvant therapy and late locoregional recurrences in different studies.

The treatment options for ONBs at their usual location and for those at ectopic sites are very much the same [1]. Combinations of surgery, radiation therapy, and chemotherapy are used. Depending on the stage and grade of the neoplasm, 5-year survival rates between 40 and 90% [3] are have been obtained in different series.

Conclusion

The challenges presented by sinonasal malignancies both in terms of their diagnosis and treatment make them an area of active research. Here, we have presented the first-ever documented case of a premaxillary olfactory neuroblastoma. This scenario highlights the importance of consideration of ONB as differential diagnosis in the lesions of the anatomical areas surrounding the sinonasal cavity.

Funding

Not received.

Declarations

Conflict of interest

None.