Case of the Month

Figure 1. AP view.  Bilateral top-to-bottom peripheral pulmonary consolidations are present. The findings are reminiscent of a photographic negative of the “butterfly pattern” seen in pulmonary edema.

Figure 2. Axial non-enhanced chest CT image (lung window) Peripheral ground glass opacities with superimposed interstitial
thickening are present through out both lung fields.

Figure 3. A transbronchial pulmonary biopsy was performed. H&E 40x.  A transbronchial pulmonary biopsy was performed. H&E 40x.

Figure 4. (A and B) AP supine and PA upright views respectively. Follow-up radiograph one month after initiation of steroid therapy shows resolution of bilateral pulmonary densities.

Eosinophilic lung diseases comprise a diverse group of pulmonary disorders that have an association with tissue or peripheral blood eosinophilia. Some authors have classified this set of disorders as primary or secondary depending on the absence or presence of a known underlying cause. Primary eosinophilic lung diseases include simple pulmonary eosinophilia, acute eosinophilic pneumonia, chronic eosinophilic pneumonia, hypereosinophilic syndrome, and eosinophilic bronchitis. Eosinophilia can also occur secondarily in patients with allergic broncho-pulmonary aspergillosis, bronchocentric granulomatosis, or parasitic or fungal infections and as a reaction to drugs or toxins. In addition, eosinophilia can be seen in patients with vasculitis, including allergic granulomatosis and angiitis. (1)

A brief review of the clinical, pathological and radiographic findings in primary eosinophilic lung diseases follows:

SIMPLE PULMONARY EOSINOPHILIA (ALSO KNOWN AS LÖFFLER SYNDROME) — Symptoms are usually mild to absent, blood eosinophilia is present. Biopsy specimens show accumulation of eosinophils in the alveolar septa and interstitium*.

Radiographically, transient migratory pneumonic patches are seen. CT shows areas of ground glass attenuation as as well as pneumonic patches. Findings usually clear within a month.

ACUTE EOSINOPHILIC PNEUMONIA — Acute onset of fever, sometimes accompanied by pleuritic chest pain and myalgias. Blood eosinophilia is initially absent, increasing as the disease progresses. A higher percentage of eosinophils than in chronic eosinophilic pneumonia is seen in BAL specimens. The average age at disease onset is approximately 30 years.
Biopsy specimens show diffuse alveolar damage with intra-alveolar and interstitial eosinophils*.

Radiographically, patchy or diffuse bilateral alveolar or mixed opacities are seen. CT shows ground-glass opacities along with interstitial thickening.

CHRONIC EOSINOPHILIC PNEUMONIA — Gradual onset of symptoms, which include fever, weight loss, cough, dyspnea, and night sweats. -Usually mild to moderate peripheral eosinophilia is seen in BAL specimens. Biopsy specimens show intra-alveolar and interstitial eosinophils. Interstitial fibrosis can be seen*.

Radiographically, peripheral Upper lobe consolidations are the most common findings. The peripheral consolidations may resemble the photographic-negative-shadows of pulmonary edema. Although this has been considered the typical radiographic appearance of chronic eosinophilic pneumonia, it is seen in less than 50% of cases. CT may show peripheral consolidations, ground-glass opacities, reticular and nodular densities or a combination of some of the above.

IDIOPATHIC HYPEREOSINOPHILIC SYNDROME — Occurs mainly in male adults. Heart and CNS involvement are the most common. GI tract, kidneys, joints and skin are occasionally involved. BAL specimens show marked eosinophilia. Persistent peripheral eosinophilia (1500/mm³) for more than 6 months or death within 6 months are diagnostic criteria. Biopsy specimens show marked infiltration of involved organs.

Radiographically, Pulmonary edema due to cardiac failure is the most common finding. CT may show nodules.

HRCT

Imaging of patients with acute eosinophilic pneumonia reveals a mixture of varying opacities usually involving both lungs. CT shows both ground-glass opacities and consolidation with peribronchovascular and septal thickening. A peripheral lung distribution has been described in 50% of cases, and an upper lung distribution is reported in 30% . Pleural effusions are common.

1. Jeong YJ, Kim KI, Seo IJ, et al. Eosinophilic lung diseases: A clinical, radiologic, and pathologic overview. RadioGraphics 2007; 27:617–639.
2. Müller NL, Fraser RS, Soo Lee K, et al. Diseases of the Lung: Radiologic and Pathologic Correlations. Philadelphia: Lippincott Williams & Wilkins, 2003: 156-162.
3. Bernheim A, McLoud T. A Review of Clinical and Imaging Findings in Eosinophilic Lung Diseases. AJR Am J Roentgenol. 2017 May;208(5):1002-1010