Perineural spread of peripheral neurolymphomatosis to the cauda equina

OBJECTIVE Neurolymphomatosis (NL) is a rare manifestation of lymphoma confined to the peripheral nervous system that is poorly understood. It can be found in the cauda equina, but extraspinal disease can be underappreciated. The authors describe how extraspinal NL progresses to the cauda equina by perineural spread and the implications of this on timely and safe diagnostic options. METHODS The authors used the Mayo Clinic medical records database to find cases of cauda equina NL with sufficient imaging to characterize the lumbosacral plexus diagnosed from tissue biopsy. Demographics (sex, age), clinical data (initial symptoms, cerebrospinal fluid, evidence of CNS involvement, biopsy location, primary or secondary disease), and imaging findings were reviewed. RESULTS Ten patients met inclusion and exclusion criteria, and only 2 of 10 patients presented with cauda equina symptoms at the time of biopsy, with 1 patient undergoing a cauda equina biopsy. Eight patients were diagnosed with diffuse large B-cell lymphoma, 1 with low-grade B-cell lymphoma, and 1 with mantle cell lymphoma. Isolated spinal nerve involvement was identified in 5 of 10 cases, providing compelling evidence regarding the pathophysiology of NL. The conus medullaris was not radiologically involved in any case. Lumbosacral plexus MRI was able to identify extraspinal disease and offered diagnostically useful biopsy targets. FDG PET/CT was relatively insensitive for detecting disease in the cauda equina but was helpful in identifying extraspinal NL. CONCLUSIONS The authors propose that perineural spread of extraspinal NL to infiltrate the cauda equina occurs in two phases. 1) There is proximal and distal spread along a peripheral nerve, with eventual spread to anatomically connected nerves via junction and branch points. 2) The tumor cells enter the spinal canal through corresponding neural foramina and propagate along the spinal nerves composing the cauda equina. To diffusely infiltrate the cauda equina, a third phase occurs in which tumor cells can spread circumdurally to the opposite side of the spinal canal and enter contralateral nerve roots extending proximally and distally. This spread of disease can lead to diffuse bilateral spinal nerve disease without diffuse leptomeningeal spread. Recognition of this phasic mechanism can lead to identification of safer extraspinal biopsy targets that could allow for greater functional recovery after appropriate treatment.

Mimics of perineural tumor spread in the head and neck

Perineural spread (PNS) is an important potential complication of head and neck malignancy, as it is associated with decreased survival and a higher risk of local recurrence and metastasis. There are many review articles focused on the imaging findings of PNS. However, a false-positive diagnosis of PNS can be just as harmful to the patient as an overlooked case. In this manuscript, we delineate and classify various imaging mimics of PNS. Mimics can be divided into the following categories: normal variants (including vascular structures and failed fat suppression), infections, inflammatory disease (including granulomatous disease and demyelination), neoplasms, and post-traumatic/surgical changes. Knowledge of potential mimics of PNS will prevent false-positive imaging interpretation, and enable appropriate oncologic management.

Perineural spread in head and neck malignancies: imaging findings - an updated literature review

Perineural spread (PNS) represents the tumor’s ability to disseminate along nerves. The aim of this article is to review the relevant literature about the PNS in head and neck tumors (H&N). The important information for imaging analysis is summarized in a diagnostic flow-chart. The pathogenesis, clinical signs, prognostic importance, and technical considerations for computer tomography and magnetic resonance imaging are briefly discussed. The anatomical pathways of the cranial nerves (CNs) and the main check-points are synthesized. Most commonly affected nerves are the trigeminal and facial, although any of the CNs may be involved. The described imaging features represent important clues for an optimal differential diagnosis. PNS worsens the prognosis and significantly changes the treatment, thus radiologists should be aware of this entity and be able to find it on imaging in the appropriate clinical context.

Recurrent Head and Neck Adenocarcinoma Presenting With a Pituitary Mass

Background: Metastasis to the pituitary gland is a rare condition. Only 1.8% of all surgically resected pituitary masses are metastases with the majority originating in the breast and lung (1). Salivary gland tumors rarely metastasize to the brain and only a few cases have been reported in the literature. Clinical Case: A 61 year-old woman presented to an outside emergency department with horizontal diplopia, blurry vision and left-sided sharp frontal headaches. MRI of the head showed a large, 2.0 x 4.6 x 1.8 cm sellar/suprasellar mass involving both cavernous sinuses, encasing the right internal carotid artery which was narrowed, and compressing the optic chiasm. Her past medical history was significant for adenocarcinoma of the left buccal mucosa and masseteric space, treated with resection in 2016, and a second resection in 2018 for recurrence followed by radiation therapy. Areas were identified where focal perineural invasion was present. She was referred to our institution for treatment recommendations for the sellar/suprasellar lesion. Laboratory testing revealed secondary hypothyroidism, adrenal insufficiency and partial diabetes insipidus, and she was started on replacement hormone therapy with levothyroxine and hydrocortisone. Neurosurgery and ENT evaluated patient and a surgical biopsy and subtotal resection via an endoscopic endonasal transsphenoidal approach was recommended for diagnosis and possible decompression of the optic chiasm. The final pathology was consistent with metastatic, high grade adenocarcinoma, supported by positive mucicarmine stain for mucin, positive immunohistochemical stain for CAM 5.2 and CK7 and negative immunohistochemical stains for the pituitary transcription factors, PIT-1 and SF-1. Conclusion: We report the second case in the literature of adenocarcinoma of the head and neck to the pituitary gland. In our case, radiological appearance of the tumor together with patient’s malignancy history led to the consideration of a pituitary metastasis. Tumors invading the cavernous sinus and causing internal carotid artery compression are rarely pituitary adenomas (2). Presence of these imaging features in patients with known risk factors for malignancy should raise suspicion for pituitary metastasis. The route of spread from the masseteric space to the sellar region remains unclear. Tumor metastasis can occur through direct invasion, hematogenous spread and perineural spread. Hematogenous spread and/or perineural spread along the trigeminal nerve are the most likely routes of metastasis in this case. Reference: (1)Javanbakht A, D’Apuzzo M, Badie B, Salehian B. Pituitary metastasis: A rare condition. Endocr Connect 2018; 7(10):1049-1057. PMID: 30139817. (2)Molitch ME et al (2012) Tumors invading the cavernous sinus that cause internal carotid artery compression are rarely pituitary adenomas. Pituitary 15(4):598–600