Diffuse large B-cell lymphoma in the sphenoid sinus mimicking fibrous dysplasia in CT and MRI

Abstract

We present a 70-year-old man with lymphoma who presented with a right eye movement disorder. CT examinations showed ‘ground-glass’ appearance extending around the right sphenoid sinus which suggested fibrous dysplasia. However, biopsy from the mass histologically proved it to be diffusing large B-cell lymphoma and positron emission tomography examinations revealed increased fluorodeoxyglucose (FDG) uptake around the right sphenoid bone and multiple spinal bones. After chemotherapy for lymphoma, abnormal FDG uptake disappeared from the body.

Background

Diffuse large B-cell lymphoma (DLBCL) is the most common pathological subtype of non-Hodgkin lymphomas (NHLs) and represents one-third of them.¹ The majority of NHL arising in head and neck sites present as an enlarged cervical lymph node and extranodal lymphoid tissue of Waldeyer's ring. NHL in paranasal sinus is uncommon, accounting for 0.17–2% of all NHL cases; it is especially rare in the sphenoid sinus.^2–4

Owing to its rarity the clinical and imaging features of NHL in the sphenoid sinus have not been established, and it is difficult to diagnose them correctly solely by imaging modalities. In this report we describe a case of DLBCL in the sphenoid sinus resembling fibrous dysplasia (FD) in CT examinations. Only pathological examinations distinguished it to be DLBCL and not FD.

Case presentation

A 70-year-old man was referred to our hospital with sudden onset of diplopia and ptosis. His medical history was unremarkable and there was no history of fever, headache or weight loss. Neurological examinations revealed right oculomotor and trochlear nerve palsy without other cranial nerve disorders. No palpable cervical lymphadenopathy was recognised and endoscopic examination of the nasal tract, pharynx and larynx was normal. There were no abnormalities in laboratory findings.

CT examinations showed the mass with ‘ground-glass’ appearance around the right sphenoid bone extending to the right medial and lateral pterygoid plates and the bilateral anterior clinoid process with thickened right middle skull base (figure 1). Radiologists strongly suggested it was FD because of its distinctive imaging features. MRI further suggested that the mass in the right sphenoid sinus was a haemorrhage occurring in the FD and that the mass was the cause of the right eye movement disorder (figure 2). In addition to FD, they reported little doubt of sarcomatous transformation from FD, although it is extremely rare.

Figure 1 Axial CT.

image shows the ‘ground-glass’ appearance around the right sphenoid bone.

Figure 2.

Axial MRI shows heterogeneously high-intensity lesion in sphenoid bone on contrast-enhanced T1-weighted MRI.

Although the radiologist's diagnosis was obtained, we thought that pathological examination was necessary to rule out malignant tumours. Four days after the first presentation to our hospital, we performed biopsy via the right sphenoethmoidal recess by endoscopic sinus surgery under general anaesthesia. Histopathological examinations including immunohistochemistry and flow cytometry showed CD20(+), Mum1(+), CD3(−) and CD5(−), thus the diagnosis was confirmed as DLBCL (figure 3). Additional investigations such as examination of bone marrow and cerebrospinal fluid showed no evidence of metastasis; however, 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) scan revealed increased FDG uptakes not only around the right sphenoid bone (SUVmax=30.87 g/mL; figure 4), but also in the sacral bone (SUVmax=37.20 g/mL) and the third and seventh dorsal vertebral bodies (SUVmax=17.14 and 15.70 g/mL; figure 5). Hence we classified the present case as Ann Arbor stage IV.

Figure 3.

Histological examination revealed diffuse large B-cell lymphoma (H&E, ×400). The tumour was composed of medium to large sized lymphoids.

Figure 4.

Axial positron emission tomography scan revealed abnormal fluorodeoxyglucose uptakes in the sphenoid bone (SUVmax=30.87 g/mL) (arrows).

Figure 5.

Sagittal positron emission tomography scan revealed metastatic fluorodeoxyglucose uptakes in the sacral bone (SUVmax=37.20 g/mL) and the third and seventh dorsal vertebral bodies (SUVmax=17.14 and 15.70 g/mL) (arrows).

Treatment

The patient was treated with R-CHOP regimen (rituximab, cyclophosphamide, doxorubicin, vincristine and prednisolone) and two courses of intrathecal methotrexate therapy for central nervous system prophylaxis.

Outcome and follow-up

After the first course of R-CHOP chemotherapy, movement of the right eye almost completely improved, and after the third course, abnormal FDG uptake disappeared from the body (figures 6 and 7). The patient has stayed recurrence-free after the start of the treatment at 1-year follow-up.

Figure 6.

Axial positron emission tomography scan revealed abnormal fluorodeoxyglucose uptakes disappeared from the sphenoid bone (arrows).

Figure 7.

Sagittal positron emission tomography scan revealed abnormal fluorodeoxyglucose uptakes disappeared from the sacral bone and the dorsal and vertebral bodies.

Discussion

Primary malignancies of the sphenoid sinus are rare. Squamous cell carcinoma and adenoid cystic carcinoma account for almost all of them, thus the lymphoma is barely found. Lawson et al⁵ reported 15 patients with primary sphenoid malignant neoplasm, but lymphoma was not presented. Cuadra-Garcia et al⁶ analysed 58 cases of sinonasal lymphoma; however, the sphenoid sinus was not the primary site of all patients. Up until now there have been only 17 reports in the English literature about primary sphenoid lymphoma.^{4 7–11}

As far as we have reviewed, 15 cases of sphenoid lymphoma including this case have been reported with detailed clinical history (table 1). Owing to the anatomical position of the sphenoid sinus, nasal obstruction or nasal discharge appeared only in five patients (33.3%), unlike its high occurrence in other paranasal sinus tumours. On the other hand, 13 patients (86.7%) initially presented with ptosis or diplopia caused by cranial nerve II, III, IV and VI palsy. Three patients had facial paraesthesia caused by nerve V (20%) and six experienced headache (40%). Tumour extension was most common in the cavernous sinus (n=6, 40%). Sphenoid sinus is surrounded by significant structures such as vital vascular, cranial nerves, optic structures, dura, pituitary and brain stem, thus patients with sphenoid sinus disease often present serious symptoms.

Table 1.

Reported cases of sphenoid lymphoma

Author (year)	Age/sex	Histology	Symptoms	Cranial nerve disturbance	Local invasion
Conley (1987)	?/?	NHL (B cell)	Diplopia	?	Left cavernous sinus
Weber (1993)	39/M	DLBCL	Nasal congestion, facial pain and paresthaesia, epiphora	V	Sellar turica
Deleu (2000)	44/M	DLBCL	Ocular motility disorder, diplopia, esotropia	V, VI (bilateral)	Clivus, cavernous sinus, ethmoid sinus
Roth (2000)	5/M	DLBCL	Sudden visual loss, optic neuropathy	II (?)	Suprasellar cavernous sinus
Van Prooyen-Keyzer (2000)	65/?	NHL (B cell)	Right nasal obstruction		Erosion of the anterior wall of the sphenoid
Lewis (2000)	4/M	Burkitt	Ptosis, headache, lethargy, vomiting	II	Cavernous sinus, infratemporal fossa
Mra (2002)	33/F	NHL (B cell)	Ocular motility disorder, diplopia, ptosis	?
Re (2004)	62/M	Burkitt-like	Diplopia, slight headache	?
Vedrine (2005)	68/F	Large B cell	Ocular motility disorder, diplopia	II, III, V and VI
Park (2007)	53/F	DLBCL	Ocular motility disorder, headache, diplopia, ptosis, mydriasis, exotropia	II	Cavernous sinus
Bisdas (2007)	83/M	NHL (B cell)	Ocular motility disorder, nasal obstruction, sinusitis, headache	II, III, IV and VI	Nasopharynx, skull base
Bisdas (2007)	79/M	NHL (B cell)	Ocular motility disorder, nasal obstruction, sinusitis, headache	II, III, IV and VI	Dura
Bisdas (2007)	64/F	NHL (B cell)	Ocular motility disorder, nasal obstruction, sinusitis, epistaxis	II, III, IV and VI
Chennupati (2009)	66/F	Burkitt	Left-sided headache	V1, 2
This report	70/M	DLBCL	Ocular motility disorder, diplopia, ptosis, mydrasis	III, IV

NHL, non-Hodgkin lymphoma; DLBCL, diffuse large B-cell lymphoma.

CT images of sinonasal lymphoma show high attenuation with permeative bone destruction without calcification, chondroid or osteoid matrix formation, haemorrhage and necrosis.^{11 12} On the other hand, there have been few reports about imaging features of sphenoid lymphomas. In our case the images of the sphenoid lymphoma resembled FD.

FD is an idiopathic benign bone disorder which was first described by Lichtenstein in 1938,¹³ and detailed aetiology is still unknown. Among FD in craniofacial bones, the mandible is involved in most cases and paranasal sinus is an uncommon lesion. CT examinations typically show radiolucent lesions with well-defined and occasionally sclerotic margins called ‘ground-glass’ pattern. On the other hand, the MR signal intensity is low to intermediate on the T1-weighted images and variable on the T2-weighted images.¹⁴ In this case, CT scan showed the tumour limited in the sphenoid bone with FD-like hypertrophy. Moreover, MRI showed an intermediate with peripheral high-intensity area on the T1-weighted images and a variable high intensity on the T2-weighted images.

Although malignant transformation of FD has been rarely reported,¹⁵ when imaging features strongly indicate FD pathological diagnosis is not always needed, especially in a difficult part to biopsy.

Otolaryngologists should be aware of this distinct sphenoid sinus image in the case of malignant lymphoma and histopathological examinations are indispensable for a definite diagnosis.

Learning points.

• Malignant lymphoma in the sphenoid sinus is rare thus distinctive imaging features have not been established.

• Sphenoid bone is surrounded by significant structures causing most patients with sphenoid sinus disease to initially present with ptosis, diplopia and headache.

• Histopathological examinations should be considered as the most important diagnostic method even when imaging modalities indicate the mass as fibrous dysplasia.