Immune-mediated necrotizing myopathy (IMNM) is characterized by proximal limb weakness, elevated creatine kinase (CK) levels, and myofiber necrosis without or with only a small amount of inflammatory cell infiltrate. There is only 1 report of hypothyroidism combined with antibody-negative IMNM to date. We aimed to describe a rare case of hypothyroidism combined with anti-signal recognition particle (SRP) IMNM for the first time and review the previous literature. A 50-year-old male, who had a 4-year history of hypothyroidism treated with levothyroxine replacement therapy, presented with progressive symmetrical proximal muscle weakness. Laboratory testing showed an elevated CK level of 6,106 U/L. Electrophysiological examination elicited carpal tunnel syndrome and myogenic damage. Muscle MRI revealed diffuse abnormal signals in both lower limbs. Given that muscle symptoms are widely recognized among hypothyroid patients, hypothyroid myopathy was initially suspected, and thyroid hormone tablets were added for a week. However, muscle weakness persisted along with an even higher CK (7,020 U/L). Quadriceps muscle biopsy was performed and indicated inflammatory myopathy. Myositis specific antibodies (MSAs) detection revealed that anti-SRP was positive. A diagnosis of hypothyroidism combined with anti-SRP IMNM was finally made. Treatment of corticosteroid and immunosuppressive agents achieved a positive clinical and biochemical response. This case indicates that hypothyroidism combined with anti-SRP IMNM is a rare clinical entity, possibly caused by a general immunologic dysregulation.
Aims: Cerebral amyloidomas (CAs) are mass-producing congophilic lesions most commonly due to λ light chain deposits, contrasting them with light chain deposition disease (LCDD) which has non-polarizable, often κ light chain deposition.
Materials and methods: Although usual histological features are well known, we detail 3 recent CAs with unusual morphological findings and review the literature specifically for these features.
Results: Two women, aged 56 and 58 years, had right cerebral white matter CAs. The biopsy of case 1 disclosed congophilic polarizable deposits with prominent dystrophic mineralization as well as scant plasma cells. Case 2 had a CA with significant multinucleated giant cell reaction to the amyloid and additionally contained an area suspicious for marginal zone B-cell lymphoma. Case 3 was a clinically unsuspected CA identified at autopsy in a 75-year-old woman that manifested as several contiguous left frontal lobe white matter erythematous, hyperemic lesions; microscopy showed nodular and concentric amyloid deposits and thick perivascular cuffs of plasma cells. Mass spectrometry proved λ light and α heavy chain amyloid deposits in all 3 cases.
Conclusion: These 3 CA cases illustrate several unusual gross and microscopic features that are discussed in context with the literature.
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