Airways Disorders NetWork Case Puzzler - June 2011

Case Puzzler | 06.23.11

A 32-year-old white man with 3 months of fatigue and cough comes to you for evaluation. He had no fever, chills, night sweats, hemoptysis, or weight loss. Normal results of a CBC and metabolic profile were noted on the laboratory exam. The patient was found to have a mild mixed obstructive and restrictive pattern on his pulmonary function tests. Chest CT scans showed the following lesions (Figs 1, 2):

Figure 1. Patient CT scan of the chest.

Figure 2. Patient CT scan of the chest.

What do the scans show and what is your differential diagnosis?

See the Answer

The “reversed halo sign” is defined as a central ground-glass opacity surrounded by a denser crescent (forming more than three-fourths of a circle) or ring-shaped (forming a complete circle) opacity that is at least 2 mm in thickness. The term reversed halo sign was coined by Kim and colleagues in their retrospective study. In the study, a comparison was made between the high-resolution CT (HRCT) scan findings in 31 patients with biopsy-proven cryptogenic organizing pneumonia (COP) and the HRCT findings of 30 patients with organizing pneumonia due to a known cause. The study found that the reversed halo sign was seen in about 20% of patients and was considered to be a relatively specific sign for diagnosing COP by CT scan. The reversed halo sign serves an important role in the diagnosis of COP, but it has also been seen in several other medical conditions. When encountering this sign, it is important to look for nodularity, which would help differentiate active granulomatous diseases from COP. Therefore, the reversed halo sign may be considered as a nonspecific sign that is encountered in various pulmonary diseases (Fig 3), and one must always analyze the differential, symptommatology, and clinical signs before establishing a definitive diagnosis.

Figure 3. Various causes of reversed halo sign.

Case follow-up: The patient underwent transbronchial biopsies and bronchoalveolar lavage, and no specific diagnosis was made. He underwent open-lung biopsy, and the diagnosis of COP was confirmed. All culture results were negative. He responded well to corticosteroid therapy, with normalization of his CT scan and pulmonary function tests.

Recommended Reading

Kim SJ, Lee KS, Ryu YH, et al. Reversed halo sign on high-resolution CT of cryptogenic organizing pneumonia: diagnostic implications. AJR Am J Roentgenol. 2003;180(5):1251-1254.

Agarwal R, Aggarwal AN, Gupta D. Another cause of reverse halo sign: Wegener’s granulomatosis. Br J Radiol. 2007;80(958):849-850.

Kumazoe H, Matsunaga K, Nagata N, et al. “Reversed halo sign” of high-resolution computed tomography in pulmonary sarcoidosis. J Thorac Imaging. 2009;24(1):66-68.

Marchiori E, Zanetti G, Hochhegger B, Irion KL. Reversed halo sign: nodular wall as criterion for differentiation between cryptogenic organizing pneumonia and active granulomatous diseases. Clin Radiol. 2010; 65(9):770-771.

Submitted by:
Diego Maselli, MD; Pooja Desa, MD; and Jay Peters, MD, FCCP

Case Puzzlers are a brief clinical vignette on various educational topics. Developed by members of the American College of Chest Physicians' NetWorks, it provides you an opportunity to sharpen your skills.

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Airways Disorders NetWork Case Puzzler - June 2011

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