Muscle Weakness Before Cancer Diagnosis: Rare Case Links Myopathy to Burkitt Lymphoma

A 42-year-old Iranian man walked into Namazi Hospital in Shiraz in March 2023 with a complaint that seemed, at first, to belong entirely to the world of neurology: his muscles were failing him. He struggled to rise from a chair, found stairs increasingly daunting, and reported diffuse aching across his limbs. He had no history of infection, toxin exposure, statin use, or strenuous exercise, and no family background of neuromuscular disease. Within weeks, that seemingly isolated muscle disorder would lead physicians to one of the fastest-growing human cancers—sporadic Burkitt lymphoma—revealing an extraordinarily rare sequence in which an immune-mediated myopathy served as the first audible alarm of an occult malignancy in an otherwise immunocompetent adult.

The case, published in the journal Cancer Reports, documents how progressive proximal muscle weakness and markedly elevated creatine phosphokinase (CPK) preceded any recognizable sign of lymphoma. On examination, the patient demonstrated symmetric weakness of the shoulder and hip girdle muscles, scoring 3 out of 5 on the Medical Research Council strength scale—able to move against gravity but not against resistance. Deep tendon reflexes were reduced, but cranial nerves, sensation, and sphincter function were intact, pointing clinicians toward a primary disease of muscle rather than nerve.

Laboratory workup sharpened the puzzle. Serum CPK, an enzyme released when muscle fibers break down, measured 900 IU/L against a reference ceiling of roughly 195 IU/L. Lactate dehydrogenase and inflammatory markers were also elevated, while a mild anemia hinted at systemic illness. Crucially, the team systematically excluded the usual suspects: antinuclear antibody, myositis-specific antibodies including anti-Jo-1, anti-Mi-2, anti-SRP, and anti-HMGCR were all negative, thyroid function and thyroid autoantibodies were normal, and testing for HIV, hepatitis B, and hepatitis C was negative. Epstein-Barr virus serology showed only evidence of past infection. No autoimmune, endocrine, toxic, or infectious explanation for the muscle injury survived scrutiny.

Electrophysiology added decisive detail. Electromyography recorded short-duration, low-amplitude motor unit potentials with early recruitment in the deltoid, first dorsal interosseous, and tensor fascia lata muscles, accompanied by prominent fibrillation potentials and positive sharp waves—a pattern characteristic of inflammatory or necrotizing myopathy. Nerve conduction studies were essentially normal, with only mild secondary axonal features, confirming that the problem lay in muscle itself rather than in the peripheral nerves supplying it. By this point, the differential diagnosis had narrowed to inflammatory myopathy, paraneoplastic myopathy, and metabolic muscle disease.

The turning point came from imaging. A contrast-enhanced computed tomography scan, obtained during the systemic evaluation, revealed enlarged left axillary lymph nodes measuring 3.5 by 2.4 centimeters along with an enlarged spleen, without focal lesions in the liver or spleen and without mass lesions elsewhere. These findings suggested a systemic lymphoproliferative process and prompted an excisional biopsy of the axillary node in April 2023. Histopathology showed complete effacement of the node’s architecture by a monomorphic population of medium-sized atypical lymphoid cells, studded with mitotic figures and interspersed tingible-body macrophages that produced the classic ‘starry-sky’ pattern—the histological signature of Burkitt lymphoma.

Immunohistochemistry sealed the diagnosis. The malignant cells expressed CD20, CD10, and BCL6, markers of a germinal-center B-cell origin, and the Ki-67 proliferation index approached 100 percent, reflecting the tumor’s hallmark near-maximal division rate. Cytogenetic analysis demonstrated rearrangement of the MYC oncogene, the molecular engine of Burkitt lymphoma. Staging studies—including bone marrow aspiration and biopsy, magnetic resonance imaging of the brain and entire spine, and cerebrospinal fluid cytology—found no marrow or central nervous system involvement, and the patient was classified as having Ann Arbor Stage III disease based on nodal involvement and splenomegaly.

One diagnostic step was deliberately sacrificed to time. Although muscle biopsy is generally considered the gold standard for classifying inflammatory myopathies, the team deferred the procedure because Burkitt lymphoma is among the most rapidly proliferative of all human malignancies, with tumor doubling times measured in days, and any delay in chemotherapy could prove catastrophic. Corticosteroids, notably, had not been given before the onset of weakness or the initial electrodiagnostic studies, ruling out the common confounder of steroid-induced myopathy; they entered the picture only afterward as part of treatment. The diagnosis of probable paraneoplastic myopathy therefore rested on the convergence of clinical findings, electrophysiology, exclusion of alternatives, and—most persuasively—what happened next.

What happened next was a striking, temporally coupled recovery. The patient began intensive therapy with the Hyper-CVAD regimen, alternating courses of cyclophosphamide, vincristine, doxorubicin, and dexamethasone with high-dose methotrexate and cytarabine, combined with rituximab targeting the CD20 antigen and standard central nervous system prophylaxis. After just the first cycle, by May 2023, his muscle strength had improved markedly and serum CPK had fallen from 900 to approximately 400 IU/L. By August 2023, upon completion of the full treatment course, CPK had normalized to 150 IU/L. Follow-up electromyography in September 2023 showed complete resolution of the previously documented myopathic abnormalities—normalized spontaneous activity, motor unit morphology, and recruitment patterns—confirmed by independent review by an experienced neurologist. At his most recent follow-up in March 2026, the patient remained asymptomatic with normal strength and no recurrence of muscle symptoms.

The clinical lesson embedded in this case concerns the phenomenon of paraneoplastic neuromuscular syndromes, in which the immune system’s response to an occult tumor spills over into attack on healthy tissue. Paraneoplastic myopathies are well described alongside solid tumors and certain hematologic malignancies, particularly Hodgkin lymphoma and intravascular large B-cell lymphoma, but their appearance ahead of sporadic Burkitt lymphoma in an immunocompetent adult appears to be exceptionally rare. Proposed mechanisms include cytokine-driven inflammation, molecular mimicry between tumor antigens and skeletal muscle proteins, and broader immune dysregulation orchestrated by the malignancy. These processes can injure muscle before any constitutional symptom, mass effect, or abnormal blood count announces the cancer, making early diagnosis genuinely difficult.

The case also distinguishes itself from prior reports of Burkitt lymphoma touching the nervous system. Earlier publications described paraplegia from spinal epidural disease, Guillain-Barré syndrome, bilateral numb chin syndrome, and oculomotor nerve palsy—all reflecting direct tumor infiltration or cranial and meningeal involvement. This patient, by contrast, had no cranial neuropathy, no sensory deficit, no cerebrospinal fluid malignant cells, and no marrow disease; electromyography pointed squarely at muscle. The neuromuscular symptoms were not a complication of advanced lymphoma but the principal reason he sought care at all. The authors acknowledge the limitations inherent in a single case report without histological confirmation of muscle involvement and with a restricted immunohistochemical panel, but argue that the full constellation of evidence strongly favors an indirect immune-mediated process tied to the lymphoma.

For clinicians, the message is pragmatic: unexplained proximal muscle weakness with elevated CPK should not be reflexively attributed to primary inflammatory myopathy when conventional investigations come back unrevealing. A careful systemic evaluation, including assessment for occult malignancy, may be warranted in atypical cases—and time matters, because Burkitt lymphoma, while ferociously aggressive, is also among the most chemosensitive cancers known. Early recognition of rare paraneoplastic presentations may mean the difference between timely, curative therapy and a fatal delay. In this instance, treating the cancer cured the muscle disease, a sequence that underscores both the diagnostic value of listening carefully to unusual symptoms and the intricate, sometimes treacherous dialogue between tumors and the immune system.

Subject of Research: Paraneoplastic myopathy as the initial presentation of sporadic Burkitt lymphoma in an immunocompetent adult

Article Title: Paraneoplastic Myopathy as a Possible Initial Presentation of Sporadic Burkitt Lymphoma in an Immunocompetent Adult: A Case Report

Article References: Khalafi‐Nezhad, A., Firouzabadi, D., mohammadkarimi, V., & Dehghanian, A. (2026). Paraneoplastic Myopathy as a Possible Initial Presentation of Sporadic Burkitt Lymphoma in an Immunocompetent Adult: A Case Report. Cancer Reports, 9(9), Article e70669. https://doi.org/10.1002/cnr2.70669

Image Credits: AI Generated

DOI: 10.1002/cnr2.70669

Keywords: Burkitt lymphoma, paraneoplastic myopathy, creatine phosphokinase, electromyography, Hyper-CVAD, MYC rearrangement, non-Hodgkin lymphoma, muscle weakness, case report, immune-mediated myopathy, oncology, neuromuscular disease