Our case report describes a case of 180° torsion of the middle lobe following upper lobe resection. Pulmonary torsion is a rare condition, with a reported incidence of 0.089 % in an American study (1). Postoperative middle lobe torsion following right upper lobectomy is the most common form of pulmonary torsion, as in our patient. Pulmonary torsion occurs most frequently in association with thoracic surgery, and less frequently following trauma or spontaneously (1–3). Pulmonary torsion generally involves hilar structures and may affect the whole lung, one or more lobes or part of a lobe. The degree of torsion is most frequently 180°, but may vary from 90° to 1,080° (3).
Our patient was asymptomatic, which has been reported in 21 % of cases of postoperative lung torsion (3). The most common symptoms and findings are acute onset of dyspnoea, fever, chest pain and cough. Underdiagnosis and misdiagnosis are common due to considerable overlap in symptoms and findings with other postoperative conditions (3). The most common is obstructive atelectasis caused by stagnation of secretions. Less common conditions are haemorrhage, infection and pulmonary embolism. Another rare complication is necrosis due to iatrogenic injury of vascular structures in the affected lobe.
Bronchoscopy was initially performed in our patient since mucus plugging is the most common cause of opacities and atelectasis, but this was not found. On the other hand, the middle lobe bronchus was uninspectable without a clear cause. According to current literature, bronchoscopy findings of an unusually angled and obstructed bronchus not caused by secretions may suggest torsion.
CXR findings that may raise suspicion of lobar torsion are opacities in an unusually oriented pulmonary lobe which may change position in a short space of time (2, 4). On CT, a tortuous lobe will usually demonstrate reduced contrast enhancement as well as consolidation and/or ground-glass opacities. A tortuous lobe may develop air retention and congestion, leading to lobe expansion and interlobular septal thickening respectively as manifestations of interstitial oedema. There is tapered obliteration of the bronchovascular structures of the lobe near the hilum and the position may be altered, as on X-ray. The development of these changes depends on the degree and duration of torsion. The radiological findings in our patient were consistent with findings previously described in literature.
We identified the condition unusually early based on radiological findings alone. The median time to diagnosis for postoperative lung torsion is 10 (2–14) days following primary surgery (3). Although a significant proportion of patients with postoperative lung torsion are asymptomatic, we believe that our patient would have developed symptoms on postoperative day 3 or 4, with development of necrosis and infection in the middle lobe.
If there is a sufficient level of suspicion of torsion, the final diagnosis is made by exploratory surgery. Treatment is detorsion or resection of the affected lobe, depending on the viability of the lobe.
Pulmonary torsion is a rare complication, but it is important to be aware of the condition as it is potentially fatal if left untreated. However, case fatality rates vary in the sparse literature regarding the subject.
Postoperative pulmonary torsion does not necessarily develop as early postoperatively as in our patient, and clinical manifestation of the condition may be delayed up to 14 days. Therefore, it is important for there to be awareness of the condition at both regional hospitals and local hospitals to which patients are admitted postoperatively.