Enfermedad relacionada con IgG4: reporte de un caso y revisión de la literatura / IgG4-related disease: a case report and literature review

Immunoglobulin G4 (IgG4-RD) -related disease is a regional or systemic fibroinflammatory disease of unknown etiology. It has a characteristic histopathological appearance of dense lymphoplasmacytic infiltrates with abundant IgG4 positive plasma cells, storiform fibrosis and obliterative phlebitis with the appearance of inflammatory swelling or swollen lesions. This entity frequently affects the pancreas, salivary glands, and lymph nodes, but it can compromise almost any structure in the human anatomy. This new disease entity includes a wide variety of diseases such as Mikulicz disease, autoimmune pancreatitis, Riedel's thyroiditis, interstitial nephritis, and retroperitoneal fibrosis. Glucocorticoid therapy can resolve clinical and pathologic abnormalities and impaired organ function. IgG4-RD was internationally recognized in 2011, and new evidence has accumulated on its pathogenesis, clinical characteristics, and treatment. However, much is still unknown about the behavior of IgG4 in vivo, the participation of this molecule in disease, and whether its role in IgG4-related disease is primary or secondary. The text below is based on a brief review of the most recent literature on this entity in relation to a clinical case.

Enfermedad relacionada con IgG4 a propósito de dos casos / Disease related to IgG4. Apropos of two cases

RESUMEN La enfermedad relacionada con IgG4 (ER-IgG4), es una enfermedad autoinmune multisistémica caracterizada por lesiones fibroesclerosantes inflamatorias formadoras de masas o pseudotumores, concentraciones elevadas de IgG4 séricas e infiltración tisular extensa por células plasmáticas IgG4 positivas. Incluye numerosas entidades que previamente se consideraban órgano-específicas. Puede afectar prácticamente a cualquier órgano, siendo los más afectados páncreas, glándulas salivales, glándulas lacrimales, ganglios linfáticos, retroperitoneo y riñones. El diagnóstico se realiza mediante una combinación de hallazgos clínicos, serológicos, imagenológicos e histopatológicos. Tiene pronóstico reservado pero con un diagnóstico precoz se logra el control y en ocasiones la regresión de la enfermedad, aunque tiende a presentar recaídas. Es una entidad infradiagnosticada debido en parte, a que fue caracterizada recientemente. Se presentan dos casos que forman parte del espectro que abarca esta entidad, la tiroiditis de Riedel y la fibrosis retroperitoneal, que una vez diagnosticados respondieron inicialmente a la terapéutica con altas dosis de corticoides (AU).

ABSTRACT The disease related to IgG4 (ER-IgG4 in Spanish) is a multi-systemic, autoimmune disease characterized by inflammatory fibro-sclerotizing lesions forming masses or pseudo tumors, high concentrations of serum IgG4 and extensive tissue infiltrations by IgG4-positive plasma cells. It includes several entities previously considered organ-specific ones. It can affect almost any organ, being pancreas, salivary glands, lacrimal glands, lymphatic ganglion, retroperineum and kidneys the most affected ones. The diagnosis is made through combining clinical, serologic, imaging and histopathological findings. It has a reserved prognosis but with an early diagnosis its control is reached, and occasionally also the disease’s remission, although it tends to have relapses. It is an underdiagnosed disease, partially due to its recent characterization. We present two cases entering the range covered by this disease, the Riedel’s thyroiditis and retroperitoneal fibrosis, both initially answering to therapy with high doses of corticoids after diagnosis (AU).