Nasopharyngeal B-cell lymphoma with pan-hypopituitarism and oculomotor nerve palsy: a case report and review of the literature

Background Primary nasopharyngeal lymphoma (NPL) is a very rare tumor of Waldeyer ring (WR) lymphoid tissue. It is challenging to differentiate lymphoma infiltration of pituitary from a pituitary adenoma, meningioma infiltration, and other sellar lesions to plan a suitable treatment strategy. We presented for the first time a unique case of NPL with an unusual presentation of oculomotor nerve palsy associated with pan-pituitary involvement in a diabetic patient. Case presentation A 64-year old diabetic woman with no previous history of malignancy presented with intermittent diplopia for about the last nine months. Severe headache, left eye ptosis and hypoglycemic episodes were added to her symptoms after a while. Further complaints include generalized weakness, loss of appetite, generalized musculoskeletal pain, and 6–7 kg weight loss within six months. Her family history was unremarkable. Physical examinations of eyes indicated left eye 3rd, 4th, and 6th nerve palsy. But, she was not anisocoric, and the pupillary reflexes were normal on both eyes. No lymphadenopathy, organomegaly and other abnormalities were found. Magnetic resonance imaging (MRI) showed a heterogeneous enhancement in the seller and suprasellar regions, enlargement of the stalk, parasellar dural enhancement and thickening of the sphenoid sinus without bone erosion. Also, both cavernous sinuses were infiltrated and both internal carotid arteries were encased by the neoplastic lesion. It suggested an infiltrative neoplastic lesion which compressed the cranial nerves. Pituitary hormone levels assessment indicated a pan-hypopituitarism. Following nasopharyngeal mucosal biopsy, the immunohistochemistry (IHC) findings revealed a low-grade non-Hodgkin’s B-cell lymphoma. Systemic workup, including cerebrospinal fluid (CSF) studies, bone marrow aspiration, chest and abdominopelvic high-resolution computed tomography (HRCT) indicated no other involvement by the lymphoma. After chemotherapy courses, central adrenal insufficiency, partial central diabetes incipidious (CDI) and central hypothyroidism have been resolved. To our best knowledge, we found 17 cases of NPL with cranial nerve palsy, 1 case of NPL with pan-hypopituitarism and no NPL case with both cranial nerve palsy and pituitary dysfunction. Conclusions The incidence of cranial neuropathy in patients with diabetes should not merely be attributed to diabetic neuropathy without further evaluation.


Background
Nasopharyngeal lymphoma (NPL) is a rare malignancy with extranodal lymphoid proliferation [1]. NPL is classified into Hodgkin lymphoma and non-Hodgkin lymphoma (NHL). NHL lymphoma accounts for 86 to 90% of all lymphoma cases [2,3]. Lymphoid tissues of the palatine tonsils, soft palate, nasopharynx, oropharyngeal wall, and base of the tongue is known as the Waldeyer's ring [1]. Previous studies have indicated that less than 10-18% of NHL cases involve the Waldeyer's ring [1,4], which about 35-37% of them were at the nasopharyngeal site [1]. In most cases, NPL appears with nasal manifestations, including epistaxis, nasal obstruction, and purulent rhinorrhea. However, it can present with a neck mass, headache, and B symptoms (i.e., weight loss, night sweats, and fever), less commonly [5].
On the other hand, 10-15% of intracranial neoplasms were attributed to pituitary tumors [6]. It has been reported that pituitary adenoma and meningioma are the most common tumors which can involve the pituitary gland. However, it is a rare site for diffuse malignant disease and metastasis [7]. The pituitary gland can be involved by metastatic lesions via the skull base, hematogenous, or meningeal spread [8]. According to a recent systematic review, the pituitary metastases (PM) are uncommon, accounting for 0.4% of intracranial metastases [9]. Almost every cancer is reported having a potential source for sellar metastasis. Lung and breast neoplasms are responsible for two-thirds of PM. The frequency of NHL involving the hypothalamus-pituitary axis is < 0.5% among PM [10]. A systematic review in 2015 stated that the most common symptom among all reported PM cases is diabetes insipidus. Anterior hypopituitarism (39.66%), visual deterioration (41.38%), cranial nerve palsies (41.38%) and headaches (32.76%) were the other symptoms which were reported. As symptomatic PM can be closely mimic a pituitary adenoma, the presentations of diabetes insipidus and/or cranial neuropathies could suggest PM rather than pituitary adenoma, especially in a rapidly developed courses, and in patients over 50 years old. Moreover, some studies have suggested that the presence of bony erosion without sellar enlargement indicates PM more than a pituitary adenoma [11]. PM has a poor prognosis and the management of patients with PM is palliative. The diagnosis of such malignancies is challenging because patients mostly presented nonspecific signs that could overshadow symptoms of hypopituitarism or diabetes insipidus, so the diagnosis is ultimately confirmed by histopathology [9,12]. Sellar masses are rarely constituted by infiltrative neoplasm (such as lymphoma), inflammatory and granulomatous diseases of the pituitary [13]. Therefore, in a patient with lymphoma, it is essential to differentiate lymphoma infiltration of the pituitary from benign lesions to plan an appropriate treatment strategy.

Case presentation
A 64-year old woman with a history of type 2 diabetes mellitus for more than thirty years and no previous history of malignancy presented with intermittent diplopia for about the last nine months, especially while going down the stairs. Diplopia was gradually increasing frequency and intensity in the previous few months. During the previous two months, the patient developed a severe headache, left eye ptosis, and hypoglycemic episodes. Further complaints include generalized weakness, loss of appetite, generalized musculoskeletal pain, and 6-7 kg weight loss within six months. Her hemoglobin A1C levels were around 7% in prior visits. Her family history was unremarkable.
In our initial physical examinations, she was obese (body mass index =34 kg/m 2 ), and her blood pressure was 120/80 mmHg. No lymphadenopathy and organomegaly were found. No other abnormalities were noted on physical examinations except for left eye ptosis (3rd, 4th, and 6th nerve palsy). But, she was not anisocoric, and the pupillary reflexes were normal on both eyes. The pupils were round and equal and reacted to light consensually and directly. Visual acuity was normal in both eyes. The other examinations of cranial nerves were normal. Magnetic resonance imaging (MRI) of the hypothalamus and pituitary indicated a heterogeneous enhancement of the sellar and suprasellar regions, enlargement of the stalk, parasellar dural enhancement with the involvement of both cavernous sinuses and internal carotid arteries, and thickening of the sphenoid sinus without any bone erosion. It was not possible to differentiate between pituitary tumor and infiltrated nasopharyngeal region. It suggested an infiltrative neoplastic lesion that compressed left III, IV and VI cranial nerves. Also, the thickening of the sphenoid sinuses and nasopharyngeal regions was seen (Fig. 1).
To rule out immunological diseases that could infiltrate cavernous sinuses and pituitary gland area (e.g., Wegener's granulomatosis, Ig G4 related disease), immunologic assays were done. All serum immunology assays except peri- In cerebrospinal fluid (CSF) analyses, protein and LDH were elevated (Table 1). CSF cytology examination showed a few small lymphoid cells with irregular nuclei.
Pathologic findings of tissue biopsy of thickened nasopharyngeal mucosa reported a low-grade lymphoma. Cell immunohistochemistry (IHC) were positive for CD20 and Bcl-2 in most lymphoid cells (B-cells). Moreover, CD3 and CD5 were positive, and CD10 was negative in some lymphoid cells (T-cells). Also, CD-23 and cyclin D1 were negative, and cell proliferation index Ki-67 was about 10%. These findings revealed a low-grade B-cell lymphoma (Fig. 2).
Chest and abdominopelvic high-resolution computed tomography (HRCT) indicated no abnormalities and lymphadenopathy. So we concluded that the final diagnosis for the current patient was a primary lymphoma originated from the nasopharyngeal mucosa by spreading the upwards areas, including both cavernous sinuses, sellar, and suprasellar regions.
She received six courses of chemotherapy with CHOP: cyclophosphamide, doxorubicin hydrochloride, vincristine sulfate, and dexamethasone plus Rituximab. Oral prednisolone (7.5 mg daily) and levothyroxine (50 μg daily) were prescribed simultaneously with chemotherapy, due to her pan-hypopituitarism. A few days after prednisolone usage, ptosis dramatically improved. MRI enhancement in the sellar and suprasellar regions and both cavernous sinuses were largely eliminated after the last chemotherapy course (Fig. 3). Besides, hematological defects were improved significantly. One month after treatment with prednisolone, the patient complained about polyuria and nocturia. Partial central diabetes insidious (CDI) was diagnosed based on more than 3 l 24-h urine volume, mild hypernatremia (Na: 147 meq/L) and low urine osmolality (urine specific gravity was 1.005 whereas the urine specific gravity in the first evaluation was 1.010). After chemotherapy courses central adrenal insufficiency, partial CDI and central hypothyroidism have been resolved.

Discussion and Conclusions
We have described a woman with type 2 diabetes mellitus and nasopharyngeal B-cell lymphoma infiltration of both cavernous sinuses and pituitary gland, who presented with the left eye ptosis (3rd, 4th, and 6th nerve palsy), severe headache, and pan-hypopituitarism.
Clinical presentations in our patient (i.e., hypopituitarism, headaches, and visual disturbances) could suggest the infiltration of the pituitary gland by lymphoma, leukemia, and metastasis to the pituitary. In our patient, A comprehensive review on the management of III nerve palsy suggested that when a patient presents with an acute onset of unilateral limitation of an eye, the defect should be categorized to "complete or partial" and "with or without the involvement of the pupil" to come to a diagnosis. Pupil-sparing in old patients with known systemic vascular disease can suggest ischemic mononeuropathy as a common cause [14] The adjacent cavernous sinus infiltration involving nerve III, IV, and VI, usually induces cranial nerve palsy in decreasing order of frequency. 6th nerve palsy is relatively uncommon because it is well sheltered in the cavernous sinus [7]. In diabetic neuropathy, multiple cranial nerve palsies are extremely rare, and pupillary reflex usually spared because the ischemic lesion is confined to the core of the nerve and does not affect peripherally situated pupillomotor fibers [15]. Although diabetic neuropathy is the most common cause of third nerve palsy, it is advisable to perform a brain MRI to exclude other causes of oculomotor nerve palsy [16].
On the other hand, poor glycemic control or rapid treatment of hyperglycemia could increase the risk of diabetic neuropathy [17]. It may have an acute onset resulting from ischemic infarction of the vasa nervorum [18]. Diabetic neuropathy was less suggested in our patient due to well-controlled diabetes, the chronic and insidious presentation of the symptoms, and multineuropathy involvement.
Sato et al. stated that isolated oculomotor nerve palsy was most frequently associated with the large B-cell lymphoma cell type. Pupil sparing oculomotor nerve palsy suggests infarction of the oculomotor nerve, as is commonly observed in patients with diabetes mellitus; despite this, there was no infarction of the oculomotor nerve on histological examination in the reported cases with lymphoma and isolated oculomotor palsy [19] These findings suggest that whether the pupil is involved or spared may depend on damage to the pupilomotor fibers in the oculomotor nerve by infiltration or compression by lymphoma. Moreover, as acknowledged by Brazis, compressive cavernous sinus lesions might spare the pupil "because they often involve only the superior division of the oculomotor nerve that carries no pupillomotor fibers, or the superior aspect of the nerve anterior to the point where the pupillomotor fibers descend in their course near the inferior oblique muscle" [15] Excluding neoplastic disorders, other etiologies of multiple cranial nerve palsy include infections (e.g., Mycobacterium tuberculosis), inflammatory diseases (e.g., sarcoidosis, vasculitis, Wegener's granulomatosis, amyloidosis, connective tissue disease, rheumatoid arthritis), vascular disease (e.g., diabetes, aneurysm, carotid artery dissection, sickle-cell disease), bone disease (e.g., Paget's disease) and trauma (e.g., closed head injury) [20].
Regarding the source of the lymphoma, pituitary lymphoma is very rare, and there is no report for extrasellar spreading in literature till now [21]. On the other hand, malignancy of WR lymphoid tissue and primary involvement of nasopharyngeal is an uncommon tumor that includes a small part of NHL and has the potential to infiltrate the adjacent tissues [1]. So, in this case nasopharyngeal lymphoma was more probable than primary CNS lymphoma.
A few studies are reporting the clinical characteristics of NH lymphomas [22,23]. Hsueh et al. reported that in 35 cases of NPL during 22 years' follow-up with the average age of 59.6 years, WBC of 12,992/mm 3 , LDH of 337.7 U/L, and the meantime from initial symptoms to diagnosis of 2.6 months, neck lymph nodes involvement or other distant involvements were detected in less than a third of patients at the time of diagnosis. Also, 14.3% of the patients were presented with B symptoms. Diffuse large B cell lymphoma was the most common pathological diagnosis of nasopharyngeal (n = 17), followed by NK/T cell lymphoma (n = 9). Extranodal marginal zone   lymphoma of mucosa-associated lymphoid tissue, mantle cell lymphoma, and small lymphocytic lymphoma was the other pathologic diagnoses [5]. To compare our patient with Hsueh et al. study, our patient had leukopenia and a longer duration from initial symptoms (i.e., diplopia) to diagnosis (about 9 months) and similar age and LDH levels. Pathological findings in our patient were compatible with mantle zone lymphoma, which was one of the lesser-known cases in NH lymphomas. Our patient's presentations were noteworthy due to her pituitary and cavernous sinus involvement, while she had no remarkable B-symptoms and nasal involvement. Unusual manifestations of a rare disease led to a prolonged diagnosis. NHL of the nasopharyngeal region is usually invasive and has a strikingly poor prognosis than other extranodal lymphomas [24]. Also, localized disease and lowgrade NPL are associated with a better prognosis [22]. Moreover, B symptoms have been reported to be associated with poor prognosis [25]. Our patient suggested having a relatively good prognosis due to her localized and low-grade disease.
There are limited data regarding epidemiologic and treatment outcomes of NH lymphoma [5]. The treatment of localized disease (stage I, II and non-bulky disease) with activity index less than 2 and normal LDH level is based on the CHOP regimen (3 to 4 cycles) plus Rituximab (if CD20 positive in immunochemistry). Based on Allam et al. study, More than 80% of patients may be successfully treated by this regimen [22]. Our patient responded to chemotherapy and resolved her hematological defects.
Glucocorticoids act as a down-regulatory signal to suppress arginine vasopressin (AVP (and corticotropinreleasing hormone (CRH (secretion via negative feedback loops, respectively. In patients with hypocortisolism, glucocorticoid deficiency stimulates CRH, and therefore AVP release. So glucocorticoid replacement could increase free water excretion and unmask the concomitant CDI [26] as showen in our patient. Although pituitary dysfunction was improved in most cases, complete recovery occurred less frequently [27]. Adrenal insufficiency, central hypothyroidism and CDI have been resolved in our patient.
In conclusion, we presented for the first time a unique case of NPL with an unusual presentation of oculomotor nerve palsy associated with pan-pituitary involvement in a diabetic patient. The incidence of cranial neuropathy in patients with diabetes should not merely be attributed to diabetic neuropathy without further evaluation.