Dados do Trabalho

Title

INFLAMMATORY PSEUDOTUMOR RELATED TO IGG4: DIFFERENTIAL DIAGNOSIS OF LYMPHOPROLIFERATIVE DISEASES

Background

IgG4-related disease (IgG4-RD) is a systemic autoimmune disorder that affects multiple
organs with clinical presentation in four phenotypes: pancreate-hepato-biliary, retroperitoneal
fibrosis/ aortitis, limited to head and neck, and systemic involvement. The aim of this article
was to describe a case of DR-IgG4 and contribute to a better understanding of this disease.

Case report

Female patient, 44 years old, with lower back pain and weight loss (10kg in 4 months).
Abdominal Computed tomography revealed attenuation of soft parts tissue, anterior to the
abdominal aorta, with expansive involvement. The abdominal magnetic resonance imaging
rshowed periaortic tissue with expansive aspect, suggesting neoplastic lymphoproliferative
injury. After exploratory laparotomy, the presence of infra-umbilical lymph node of 2cm
diameter, small ascites and palpable retroperitoneal mass (7cm) was reported. The mass was
biopsied and revealed Storiform myofibroblasts or fibroblasts proliferation in fibrous stroma
with extension to perinodal tissues, mixed vascular proliferation and inflammatory infiltration
consisting of plasma cells, lymphocytes, histiocytes and neutrophils characterizing
aInflammatory myofibroblastic tumor (inflammatory pseudotumor). Immunohistochemistry:
Presence of Antibodies Ki-67 <1%, CD138, IgG4 (MRQ-44-30 cells / CGA), IgG, being
histologically IgG4 related disease. Serum IgG4 dosage: 68.7 (Reference Value: 3 - 201),
ESR: 79. The patient was treated with prednisone 1mg/ kg/ day and rituximab evolving with
clinical and laboratory improvement.

Conclusion

The pathogenesis of IgG4-RD is unclear. There is a decrease in Thelper1/ Thelper2 cells and
increase in TRegulators, with co-activation of B cells expressing IgG4, but their role is
unknown, probably play an anti-inflammatory role in response to a trigger.
Clinical manifestations may occur in almost all organs or systems. Patients often have a mass
on the affected organ, such as a retroperitoneal mass or diffuse organ enlargement.
Retroperitoneal fibrosis is one of the most common presentations of IgG4-RD, responsible
for the most cases of retroperitoneal fibrosis previously considered "idiopathic".
Diagnosis is based on histopathological, clinical, serological and radiological findings.
However, when a retroperitoneal fibrosis manifests, it is essential to make the differential
diagnosis with lymphoproliferative diseases, due to the similarity in the radiological findings.
Histopathology shows dense lymphoplasmacytic infiltrate, fibrosis, and obliterative phlebitis
is somewhat characteristic and the serum increase of IgG4 is present in only 60% of the
cases.
The treatment of IgG4-RD may change according to the affected organ, and glucocorticoids
are the first line, but reports indicate long-term benefits with rituximab.