Magnetic resonance imaging of intercranial plasmocytic granuloma

IgG4-Related Disease in the Frontal Convexity Concomitant with Smoldering Multiple Myeloma: A Case Report and Review of the Literature Regarding Therapeutic Implications

BACKGROUND

We have reported an extremely rare case of a frontal convexity tumor diagnosed as IgG4-related disease (IgG4-RD) with unique neuroradiological images.

CASE DESCRIPTION

A 64-year-old man with a history of monoclonal gammopathy of undetermined significance and conservative treatment had presented with a left facial spasm. Computed tomography showed a high-density round tumor with perifocal edema in the right frontal convexity. Magnetic resonance imaging demonstrated unique findings, including low signal intensity on T1- and T2-weighted, fluid-attenuated inversion recovery, and diffusion-weighted images, with slight gadolinium enhancement. The tumor was totally removed via right frontal craniotomy. It had been located in the subdural space, was not adherent to the dura, and was less vascular than meningiomas. Histological investigation demonstrated plasma cells that were strongly positive for IgG4 and contained κ and λ light chains at a ratio of 1.5:1. The serum IgG4 level was elevated. The tumor met the diagnostic criteria for IgG4-RD. The patient was followed up for 3 years during postoperative adjuvant steroid therapy. The steroid therapy was discontinued, and during the next 4 years, neither tumor recurrence nor symptoms were observed.

CONCLUSION

Intracranial IgG4-RD with smoldering monoclonal gammopathy of undetermined significance is extremely rare. We reviewed the differential diagnosis of plasma cell granuloma and plasmacytoma, therapeutic implications, and clinical outcomes. Complete resection of a conspicuous and solitary IgG4-RD lesion in the frontal convexity is simple and could provide a cure with less-aggressive adjuvant therapy.

Primary intracranial plasma cell granulomas presenting as malignant neoplasms

Plasma cell granuloma (PCG) is an uncommon non-neoplastic mass lesion of unknown etiology. It is characterized by a polyclonal proliferation of chronic inflammatory cells, mostly mature plasma and other mononuclear cells. PCGs arising in the central nervous system are particularly rare. We report two additional cases of intracranial PCG exclusively involving the brain parenchyma. A 47 year-old woman, presenting with partial motor seizures and fluent aphasia, underwent complete excision of a well-demarcated, enhancing left parietal mass. The second patient was a 56 year-old man presenting with headaches and right-sided weakness who underwent stereotactic biopsy of an ill-defined, heterogeneously enhancing lesion in the left basal ganglia. Immunohistochemical analysis of surgical specimens showed polyclonal plasma cells and mature lymphocytes but no etiological agent. A histopathologic diagnosis of intracranial PCG was made in both cases. PCG should be part of the differential diagnosis of enhancing mass lesions of the brain. The etiology and natural history of these tumor-like lesions is not fully understood. Complete surgical excision appears to be curative. Lesions where total resection is not possible may benefit from adjuvant treatment including corticosteroids and possibly radiation therapy.

Inflammatory pseudotumors of the central nervous system: report of 3 cases and a literature review

Inflammatory pseudotumors (IPs), mostly benign lesions characterized by fibrotic ground tissue and polyclonal mononuclear infiltrate, may affect all organ systems. IPs originating in the central nervous system (IP-CNS) are very rare, and their distinct histopathologic features are poorly characterized. Three otherwise healthy patients (age 8, 15, and 17 years) presented with focal neurologic symptoms (seizures, n = 2; headaches, n = 1), corresponding to a left temporal, left occipital, and left frontal IP, respectively, extending from meningeal structures into brain tissue. After resection, no recurrence was observed in patient 1 during 5 years of follow-up, whereas patient 2 developed a rapidly progressive local recurrence and a second intracerebral lesion despite antiviral, immunosuppressive, antibiotic, and radiation therapy. In patient 3, who also showed local recurrences, sequential histopathologic investigations revealed transformation to a semimalignant fibrohistiocytic tumor. In this patient, anaplastic lymphoma kinase (ALK) expression was also positive, whereas it was negative in patient 1. A detailed literature analysis confirmed that most IP-CNS arise from dural/meningeal structures (n = 34). Intraparenchymatous (n = 7), mixed intraparenchymatous/meningeal (n = 4), and intraventricular lesions (n = 7) or IP extending per continuitatem from intracerebral to extracerebral sites (n = 5) were rare. The recurrence rate was 40% within 2 years in general. It was increased after incomplete resection and in female patients (multivariate Cox regression model, P < 0.02). Although rare, IP-CNS are important differential diagnoses among tumor-like intracranial lesions. Their potential risk of malignant transformation and high risk of recurrence necessitate close follow-up, especially when resection is incomplete. Prospective multicenter trials are needed to optimize classification and treatment of this rare inflammatory lesion.