Mixed Connective Tissue Disease: A Rare Disease with Many Faces

Abstract

Chaimaa Zeroual*, Afaf Aallam, Safaa Mourabit, Mina Moudatir, Khadija Echchilali and Hassan Elkabli

Introduction: Mixed connective tissue disease (MCTD) is a rare autoimmune disease characterized by overlapping clinical manifestations of several systemic connective tissue diseases and the presence of anti-U1RNP antibodies. This study aims to describe the clinical, immunological, and evolutionary features of patients with MCTD.

Methods: A retrospective descriptive study conducted over 5 years (2020–2024) in the internal medicine department of Ibn Rochd University Hospital Center in Casablanca, including 9 female patients meeting Kasukawa’s criteria.

Results: All patients were female, with a mean age at diagnosis of 41.3 years. Raynaud’s phenomenon was the most frequent inaugural sign. Pulmonary involvement was present in 66.6% of cases, with one-third of these patients exhibiting fibrotic changes. Anti-U1RNP antibodies were positive in 100% of patients. Evolution towards a differentiated connective tissue disease (lupus or systemic sclerosis) was observed in 77.7% of cases. The overall prognosis was favorable, despite one death related to a paraneoplastic syndrome.

Conclusion: MCTD remains a rare disease with variable clinical expression, requiring particular diagnostic vigilance. Early identification of evolving forms and multidisciplinary monitoring are essential to prevent complications and guide treatment

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