Introduction

Mononeuropathy multiplex (MM) is a painful neuropathy involving the sensory and motor peripheral nerves in two separate nerve areas simultaneously [1, 2].
The differential diagnoses associated with MM include a wide range of systemic disorders such as diabetes mellitus, vasculitis, amyloidosis, systemic lupus erythematosus (SLE), viral infections such as AIDS (acquired immunodeficiency syndrome), hepatitis, parvovirus B19, multiple compression neuropathies and paraneoplastic syndromes [3-6]. One possible, albeit rare, cause is lymphoma [7].
Intravascular lymphoma(IVL), a rare B-cell lymphoma, involves an aggressive intravascular overgrowth of neoplastic B-lymphocytes in small to medium-sized vessels [8]. The resulting deficits in vascular supply to organs produce a range of systemic and neurologic symptoms that often overlap with those of other diseases, especially vasculopathies[9]. The most common symptoms include skin lesions and fever/chills. The majority of patients with intravascular lymphoma who develop neurologic symptoms show central nervous symptoms such as cognitive or motor deficits [9]. A systematic review of reported cases estimated that the peripheral nervous system was involved in a minority of 9.5% of patients who experienced some degree of involvement as a late finding discovered only after diagnosis[9].
Diagnosing intravascular lymphoma is challenging because it is rare and it presents with a wide variety of symptoms[11]. Moreover, its diagnosis relies on clinical suspicion and tissue biopsy [10]. On the other hand, this type of non-Hodgkin lymphoma is lethal within a year unless diagnosed and treated early [11]. These issues highlight the importance of early accurate diagnosis and treatment and the role of a high index of suspicion for this life-threatening disease in patients presenting with symptoms suggesting vascular involvement [11-13].
Since intravascular lymphoma and its neurologic manifestations are rare; and the disease course is short with a fatal outcome, the study of their clinical course is limited to case reports and case series[11]. Previous case reports have reported patients with intravascular lymphoma presenting with peripheral neuropathy; However, MM as the primary presentation is extremely rare [7, 14-18]. Previously reported patients were diagnosed in post-mortem autopsies after an initial misdiagnosis of vasculitis [18, 19].
We report a case in which MM was the core manifestation of intravascular large B-cell lymphoma(IVLBCL) and was diagnosed based on a nerve biopsy.