Muller Journal of Medical Sciences and Research

: 2018  |  Volume : 9  |  Issue : 1  |  Page : 39--40

Costophrenic angle blunting: Always abnormal?

Venkatraman Indiran 
 Department of Radiodiagnosis, Sree Balaji Medical College and Hospital, Chennai, Tamil Nadu, India

Correspondence Address:
Dr. Venkatraman Indiran
Department of Radiodiagnosis, Sree Balaji Medical College and Hospital, 7 Works Road, Chromepet, Chennai - 600 044, Tamil Nadu

How to cite this article:
Indiran V. Costophrenic angle blunting: Always abnormal?.Muller J Med Sci Res 2018;9:39-40

How to cite this URL:
Indiran V. Costophrenic angle blunting: Always abnormal?. Muller J Med Sci Res [serial online] 2018 [cited 2020 Nov 28 ];9:39-40
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Full Text

Dear Editor,

Costophrenic (CP) angle or the costodiaphragmatic recess is one of the review areas in reading a chest radiograph systematically. Normally, the CP angle is acute and sharp. Normal CP angle measures approximately 30°. Alteration in shape and angle may occur as part of blunting and usually indicates pleural or pulmonary disease. Isolated blunting of the CP angle is usually considered to represent pleural disease such as small pleural effusion or mild pleural thickening. Chronic obstructive pulmonary disease with hyperinflation may also alter the CP angle due to diaphragmatic flattening. Deep CP angles may occur in tension pneumothorax.

Classically, isolated blunting of the CP angle on chest radiograph (posteroanterior view) has been taught to represent about 200 ml of the pleural fluid.[1] Suspicion of the pleural fluid may be ascertained using lateral decubitus radiograph or ultrasound examination.

However, there are some instances where we encounter such mild blunting of the CP angles in an otherwise normal chest radiograph, in people presenting for preventive health checkups, preemployment, or preimmigration screening [Figure 1]. We had always raised the possibility of small pleural effusion or mild pleural thickening, based on the classical teaching. However, a recent study by Matsumoto-Yamazaki et al. tried to assess the radiographic measurements, spirometry, and clinical symptoms in such subjects with a stable blunt CP angle during company medical check.[2] Subjects with stable blunt CP angles were those who had blunted CP angle at least 3 consecutive years without any progression. Although exact pathophysiological basis of blunt CP angle could not be identified, possible explanation was the inhomogeneity of regional ventilation due with flow-to-volume dysanapsis.{Figure 1}

The essential learning point would be that stable blunt CP angles may be seen without significant pulmonary and pleural disease, and it would be prudent not to undertake extensive investigations for blunt CP angles seen, especially those seen in the asymptomatic patients undergoing preventive or screening checkups. Screening ultrasound of the CP angles alone may suffice in such situations. Larger studies of stable blunt CP angle seen in master health checkups in Indian setting can throw more light on this particular scenario.

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1Na MJ. Diagnostic tools of pleural effusion. Tuberc Respir Dis (Seoul) 2014;76:199-210.
2Matsumoto-Yamazaki M, Ohwada A, Shiota S, Takahashi K. A stable blunt costophrenic angle in healthy subjects, associated with dysanapsis and airflow limitation. J Pulm Respir Med 2014;4:210. doi:10.4172/2161-105X.1000210.