Cough-induced intercostal lung and hepatic hernia

Clinical History

The patient was referred because of a mass in the right lateral region at thoracic abdominal level, with a 2-month evolution after a bout of coughing. Physical examination revealed a soft, non-reducible and painful mass.
The patient had a history of asthma treated with inhaled corticosteroids.

Imaging Findings

Total bone scintigraphy with MDP-TC99m showed an increase in the compound radius capturing at the level of the right eighth costovertebral joint, ninth and tenth ribs compatible with recent fracture (Figure 1). CT confirmed a defect in the right lower thoracic wall with fracture of the eighth, ninth and tenth ribs, with diastasis of the intercostal space between the eighth and ninth ribs, and projection towards the subcutaneous soft tissue of the lateral basal segment of the right inferior pulmonary lobe and right hepatic lobe (Figure 2).
The post-operative chest CT follow-up study showed projection of the right hepatic lobe outside the limits of the abdominal wall (Figure 3).

Discussion

Intercostal hernias are a rare condition [1]. They may be congenital or acquired. The latter occur after a penetrating trauma or surgery, and less frequently spontaneously [2, 3]. However, spontaneous hernias occur in patients with predisposing factors such as chronic obstructive pulmonary disease, asthma treated with steroids and diabetes mellitus [4]. Also, patients with severe chronic cough may develop intercostal muscle tears and even costal fractures [1, 5]. Positive intrathoracic pressure during inspiration, coughing, vomiting and defecation can force the intrathoracic or intraabdominal content to exit through the weakened areas of the thoracic wall [1]. Anatomically, there are two weak sectors on the thoracic wall; an anterior sector, from the costochondral junction to the sternum, due to the absence of the external intercostal muscle; and a posterior sector, from the costal angle to the vertebra because of the absence of the internal intercostal muscle [1]. Spontaneous hernias are more common in the anterior region, since in the posterior region the paravertebral muscles are resistant to herniation.
They generally appear as a soft, painful mass, which may increase in size after exertion, coughing, or Valsalva maneuver [4, 6, 7]. Intercostal hernias are at risk of incarceration and strangulation [1, 2].
Regarding imaging studies, both computed tomography and ultrasound may be applied, although the latter cannot exactly determine the hernial content. Computed tomography does not only reveal the hernia and its content, but it also assesses the exact location and size of the costal wall defect, relevant for surgical planning [1, 3]. The radiological presentation of pulmonary intercostal herniation consists of a subcutaneous hyperlucency containing pulmonary vessels, corresponding to a localized collection of air and contrasting with disseminated bubbles as seen in subcutaneous emphysema [3]. However, X-ray studies do not usually provide enough information about the hernia, even though they can provide data over associated injuries; besides, in the intercostal pulmonary hernias, they may fail to show the herniation of lung parenchyma unless it is tangential to the X-ray beam [8, 9].
The treatment is surgical. Regarding the techniques, it is preferable to use mesh after reducing the hernia, since applying sutures near the ribs has been associated to recurrence [1].

Differential Diagnosis List

Final Diagnosis

Intercostal lung and hepatic hernia

URL:	https://www.eurorad.org/case/10261
DOI:	10.1594/EURORAD/CASE.10261
ISSN:	1563-4086