Paraneoplastic neurological syndrome: an evolving story

Case report: PCA-2-associated encephalitis with different clinical phenotypes: a two-case series and literature review

Purkinje cell cytoplasmic antibody type 2 (PCA-2), identified in 2000, targets the widely distributed microtubule-associated protein 1B in the central and peripheral nervous systems, leading to diverse clinical phenotypes of neurological disorders. We report two cases of PCA-2-associated encephalitis, each presenting with distinct onset forms and clinical manifestations, thereby illustrating the phenotypic variability of PCA-2-related diseases. The first patient was diagnosed with PCA-2-associated autoimmune cerebellitis and undifferentiated small cell carcinoma with metastasis in mediastinal lymph nodes of unknown primary origin. The second patient was diagnosed with PCA-2-associated limbic encephalitis. Our findings underscore the superior sensitivity of positron emission tomography-computed tomography over brain magnetic resonance imaging in the early detection of PCA-2-associated encephalitis. Given the high risk of relapse and suboptimal response to traditional immunotherapy in PCA-2-related neurological disorders, this study highlights the need for a deeper understanding of their pathogenesis to develop more effective treatments to control symptoms and improve patient prognosis.

Paraneoplastic Cerebellar Degeneration Associated with Breast Cancer: A Case Report and a Narrative Review

Paraneoplastic neurological syndromes (PNSs) are an uncommon complication of cancer, affecting nearby 1/10,000 subjects with a tumour. PNSs can involve all the central and peripheral nervous systems, the muscular system, and the neuromuscular junction, causing extremely variable symptomatology. The diagnosis of the paraneoplastic disease usually precedes the clinical manifestations of cancer, making an immediate recognition of the pathology crucial to obtain a better prognosis. PNSs are autoimmune diseases caused by the expression of common antigens by the tumour and the nervous system. Specific antibodies can help clinicians diagnose them, but unfortunately, they are not always detectable. Immunosuppressive therapy and the treatment of cancer are the cornerstones of therapy for PNSs. This paper reports a case of PNSs associated with breast tumours and focuses on the most common paraneoplastic neurological syndromes. We report a case of a young female with a clinical syndrome of the occurrence of rigidity in the right lower limb with postural instability with walking supported and diplopia, with a final diagnosis of paraneoplastic cerebellar degeneration and seronegative rigid human syndrome associated with infiltrating ductal carcinoma of the breast.

Spontaneous regression of small cell lung cancer associated with Lambert-Eaton Myasthenic Syndrome: Case report

Spontaneous regression (SR) of cancer is very rare, especially of small cell lung cancer (SCLC). Recently, an association of paraneoplastic neurological syndrome (PNS) has been reported as a cause of SR of cancer, and onconeural antibodies are a possible factor in the SR of cancer associated with PNS. We herein report the first case of SR of SCLC combined with anti-P/Q-type of voltage-gated calcium channel (VGCC) antibody-positive Lambert-Eaton myasthenic syndrome (LEMS), a subtype of PNS. This case report suggests that SCLC may be spontaneously reduced by an autoimmune response induced by VGCC antibodies associated with LEMS. Our finding may help elucidate the mechanisms that inhibit tumor growth and cause the regression of tumors.

Autoimmune Axonal Neuropathies

OBJECTIVE

This article reviews autoimmune axonal neuropathies, their characteristic clinical features, disease and antibody associations, appropriate ancillary testing, treatment, and prognosis.

LATEST DEVELOPMENTS

In 2021, the American College of Rheumatology and the Vasculitis Foundation released new summary guidelines for the treatment of antineutrophil cytoplasmic autoantibody-associated vasculitides. In addition, novel autoantibodies have been recently identified; they are often paraneoplastic and associated with axonal neuropathies.

ESSENTIAL POINTS

Recognition of autoimmune axonal neuropathies is important because of the potential for effective treatment to either reverse deficits or slow the progression of disease. It is necessary to properly assess for associations with other systemic disorders (eg, systemic vasculitis, connective tissue disease, neoplasm) so that adequate treatment for both neurologic and non-neurologic aspects of the disease can be initiated.

Diagnosis and Treatment of Paraneoplastic Neurologic Syndromes

Paraneoplastic antibody syndromes result from the anti-tumor antibody response against normal antigens ectopically expressed by tumor cells. Although this antibody response plays an important role in helping clear a nascent or established tumor, the engagement of antigens expressed in healthy tissues can lead to complex clinical syndromes with challenging diagnosis and management. The majority of known paraneoplastic antibody syndromes have been found to affect the central and peripheral nervous system. The present review provides an update on the pathophysiology of paraneoplastic neurologic syndromes, as well as recommendations for their diagnosis and treatment.

High-grade B-cell lymphoma with gastroduodenal involvement showing paraneoplastic cerebellar degeneration: a case report

Background

Paraneoplastic cerebellar degeneration (PCD), which displays ataxia and other cerebellar symptoms, is the most common paraneoplastic neurological syndrome (PNS). PCD is more likely to occur in individuals with small cell lung cancer (SCLC), gynecological malignancies, and Hodgkin disease, but it is rarely associated with non-Hodgkin lymphoma (NHL).

Case Description

We report a case of PCD accompanying high-grade B-cell lymphoma embedded in an individual's stomach and duodenum, who also presented with acute onset of gait ataxia and slurred speech. The results of the common laboratory tests for neurological disorders, including the paraneoplastic antibody test, were negative. The key to the accurate diagnosis was the positron emission tomography/computed tomography findings. The final diagnosis of high-grade B-cell lymphoma was unclear until the performance of repeated esophagogastroscopy with multipoint deep excavation biopsies. After standard chemotherapy, the patient's gastric tumor was significantly alleviated and cerebellar syndrome was significantly improved.

Conclusions

This case highlights the challenges of diagnosing PNS associated with occult malignancy. PNS patients may present with a variety of neurological disorders; Thus, if any unexplained neurological symptoms appear after a series of specific laboratory and imaging tests, a diagnosis of PNS should be taken into consideration in the differential diagnosis list, as it may help clinicians identify asymptomatic malignancies and ensure patients receive correct treatments in a timely manner. A high-quality endoscopic biopsy is essential, as it helps hematologists make an accurate diagnosis of lymphoma with gastroduodenal involvement based on pathology.