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Weekly Chest CasesArchive of Old Cases

Case No : 1478 Date 2026-02-16

  • Courtesy of Ji Young Song, Taehee Lee, Ji Young Lee / Seoul National University Hospital
  • Age/Sex 66 / F
  • Chief ComplaintBlod-tinged sputum
  • Figure 1
  • Figure 2
  • Figure 3
  • Figure 4

Diagnosis With Brief Discussion

Diagnosis
Microscopic polyangiitis
Radiologic Findings
Fig 1. Chest PA image shows multifocal faint GGOs in both lungs
Fig 2. Non–contrast-enhanced chest CT demonstrates bilateral, patchy, and geographic ground-glass opacities involving both lungs.
Fig 3. Chest CT obtained 6 months before presentation shows less extensive and less dense bilateral ground-glass opacities, indicating partial interval improvement.
Fig 4. Follow-up chest CT obtained 1 month after the initial visit demonstrates a slight decrease in the extent and attenuation of the ground-glass opacities, consistent with a waxing-and-waning course.
Fig. 5. Chest CT obtained 2 months after initiation of systemic corticosteroid therapy demonstrates a marked decrease in the extent and attenuation of the previously noted ground-glass opacities.
Brief Review
Antineutrophil cytoplasmic autoantibody (ANCA)–associated vasculitis (AAV) is a rare disease characterized by necrotizing vasculitis affecting small vessels without immune complex deposition. Microscopic polyangiitis (MPA) is one of the major subtypes of AAV, along with granulomatosis with polyangiitis (GPA) and eosinophilic granulomatosis with polyangiitis (EGPA).
MPA is characterized by the absence of granulomatous inflammation, which is typically seen in GPA, and by a strong association with myeloperoxidase (MPO)–ANCA positivity. Clinically, MPA most frequently involves the kidneys and lungs, with necrotizing glomerulonephritis occurring in up to 90% of patients and pulmonary manifestations reported in approximately 25%–50%. Unlike GPA, upper airway and sinonasal involvement are uncommon.
MPA frequently presents with interstitial lung disease (ILD), most commonly manifesting as a usual interstitial pneumonia (UIP) pattern with honeycombing and traction bronchiectasis. ILD prevalence in MPA is particularly higher in Asian populations, probably due to the higher MPO-ANCA–positive population.
In addition to ILD, another major thoracic manifestation of MPA is diffuse alveolar hemorrhage (DAH) caused by pulmonary capillaritis, which typically appears as bilateral ground-glass opacities or consolidations on imaging.
According to the 2022 ACR/EULAR classification criteria, p-ANCA (MPO-ANCA) positivity and pulmonary fibrosis or ILD on chest imaging serve as key discriminators for MPA, whereas c-ANCA positivity and nasal involvement are considered negative factors.
References
1. Suzuki A, Sakamoto S, Kurosaki A, et al. Chest High-Resolution CT Findings of Microscopic Polyangiitis: A Japanese First Nationwide Prospective Cohort Study. AJR Am J Roentgenol. 2019;213(1):104-114.
2. Kwon J, Choi YW, Kim H, Yoo SJ. Thoracic Manifestations of ANCA-associated Vasculitis: Review of the 2022 American College of Rheumatology-European Alliance of Associations of Rheumatology Classification Criteria. Radiographics. 2025;45(4):e240089.
Keywords

No. of Applicants : 83

▶ Correct Answer : 9/83,  10.8%
  • - , Japan Z Y
  • - , Italy PAOLO BALDASSARI
  • - , China FANG YING GEN
  • - Chonbuk National University Hospital , Korea (South) YONG HWAN JO
  • - The University of Tokyo Hospital , Japan TOSHIHIRO FURUTA
  • - The Catholic University of Korea Yoeuido St. Mary , Korea (South) OHMIN KWON
  • - Other , Korea (South) CHAEHUN LIM
  • - , Japan TOMOHIRO KAWAJI
  • - Chonnam National University Hospital , Korea (South) JAEBONG YANG
▶ Correct Answer as Differential Diagnosis : 15/83,  18.1%
  • - Saitama-Sekishinkai Hosptal , Japan MIHOKO YAMAZAKI
  • - , Korea (South) KYUNG HYUN WOO
  • - Vita Hospital , Brazil DIOGO LAGO PINHEIRO
  • - Seoul Medical Center , Korea (South) HYUK GI HONG
  • - Osaka University , Japan AKINORI HATA
  • - Chiba University Hospital , Japan HIROKI MIYAZAKI
  • - University of Yamanashi , Japan HIROAKI WATANABE
  • - Shiga General Hospital , Japan YUSAKU MORIBATA
  • - Korea University Anam Hospital , Korea (South) KYU-CHONG LEE
  • - Kobe Children , Japan SHUHEI NORIMOTO
  • - Yonsei University,Severance Hospital , Korea (South) SEO BUM CHO
  • - Ehime University , Japan TOMOHISA OKADA
  • - University of Yamanashi , Japan KOJIRO ONOHARA
  • - , Japan YUJI OHIZUMI
  • - , Japan YUKIHISA TAKAYAMA
▶ Semi-Correct Answer : 11/83,  13.3%
  • - The University of Tokyo Hospital , Japan ISSEI FUKUDA
  • - Shiga University of Medical Science , Japan AKITOSHI INOUE
  • - Central Hospital Atasehir Istanbul , Turkey ARMAGAN SARAC
  • - Secomedic Hospital , Japan FUMINORI MIYOSHI
  • - Ajou University Hospital , Korea (South) HYUNSEUNG LEE
  • - Jichi Medical University, School of Medicine , Japan MITSURU MATSUKI
  • - Aichi Medical University , Japan HIROAKI OKADA
  • - Kyung Hee University Medical Hospital , Korea (South) TAE JUN PARK
  • - Ichinomiya Nishi Hospital , Japan Takao Kiguchi
  • - Ehime University , Japan KOTARO MATSUMOTO
  • - Jiangsu province hospital , China WANGJIAN ZHA
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