Anti-MDA5 antibody-positive rapidly progressive interstitial pneumonia without cutaneous manifestations

Abstract

A 47-year-old man was referred to our hospital with a 1-month history of fever and dyspnea after inhalation of insecticide in a confined space. We diagnosed rapidly progressive interstitial pneumonia. High-dose methylprednisolone, tacrolimus, and intermittent infusion of cyclophosphamide were administered. His condition rapidly deteriorated; therefore, extracorporeal membrane oxygenation therapy was performed. Unfortunately, he died 69 days after admission. Although typical skin findings suggestive of dermatomyositis were absent, anti-melanoma differentiation-associate gene (anti-MDA5) antibody was positive. Our findings suggest that in patients with hyperferritinemia and rapidly progressive interstitial lung disease (RP-ILD) demonstrating random ground glass shadows and peripheral consolidations by high-resolution computed tomography (HRCT) even if skin manifestations related to dermatomyositis are not complicated, we should assume anti-MDA5 antibody-positive interstitial pneumonia.

Keywords: ARS, anti-aminoacyl-tRNA synthetase; Anti-MDA5, anti-melanoma differentiation-associate gene; Anti-melanoma differentiation-associated gene 5 antibody; CADM, clinically amyopathic dermatomyositis; Clinical amyopathic dermatomyositis; Extracorporeal membrane oxygenation; HRCT, high-resolution computed tomography; IVCY, intravenous cyclophosphamide; RIG-I, retinoic acid inducible gene-I; RP-ILD, rapidly progressive interstitial lung disease; Rapidly progressive interstitial pneumonia.

Fig. 1

Chest X-ray and chest plain computed tomography. A: Chest radiograph on admission shows bilateral ground glass opacities. B, C, D. Chest CT scan shows random ground glass opacities in the lower lung fields. Honeycombing and pleural effusion are not present.

Fig. 2

Cellulo-myxomatous alveolitis. The photomicrograph with HE staining shows notable inflammatory cell infiltration of the alveolar wall with reactive pneumocyte hyperplasia (scale bar, 10μm).

Fig. 3

Cellulo-myxomatous alveolitis with desquamative pneumocytes and fibrinous exudates. Photomicrograph of lung sections with HE and Alcian blue/PAS staining shows mixed cellulo-myxomatous change of alveolar wall with pneumocyte hyperplasia and fibrinous exudates (arrows). High power view shows findings of desquamative and atypical pneumocytes (black arrow head) with some eosinocyte infiltrations (blue arrow head) (scale bar, 100μm).

Fig. 4

Disease course of the patient over time.