Imaging of trichoptysis - how a radiologist can help?

Trichoptysis is a rare symptom, but pathognomonic of a teratoma having a bronchial communication. Thoracic teratomas are usually located within the anterior mediastinum, but rarely present with trichoptysis, as transpleural erosion of a mediastinal teratoma into lung and hence bronchial tree is exceedingly rare. We report the characteristic radiological and clinical features in one such case with ruptured mature mediastinal teratoma having a bronchial communication leading to trichoptysis. Only nine cases of trichoptysis have been reported in the literature as yet, but a fistulous communication with the bronchial tree on computed tomography, as seen in the present report, has not been demonstrated in any of these preceding reports. Histopathological sample obtained during the surgery further confirmed the presence of a mediastinal teratoma with transpleural broncho-pulmonary communication.

INTRODUCTION

Mediastinal teratomas are germ cell tumors arising from ectopic pluripotent stem cells.[1] Most teratomas are immature in nature, and solid lesions having few focii of cystic degeneration, only 2-4% of lesions are predominantly cystic (the more mature and well differentiated) in nature [12] Whatever the case might be, these lesions usually present with signs and symptoms attributable to “mass effect.” On rare occasions, however, teratomas may erode into adjacent structures, such as the pleural space, pericardium and lung and/or trachea-bronchial tree.[2] The presenting symptom in the latter scenario is one of expectoration of mature hair follicles known as “trichoptysis.”[2] The incidence of this complication is exceedingly rare and is seen more commonly with cystic than with solid lesions.[3] Trichoptysis as a symptom has been described in only nine cases as yet but remains pathognomonic for a mediastinal teratoma having broncho-pulmonary communication.[3] Though computed tomography (CT) scan features of such a lesion have been described previously, none of these reports demonstrates a “lesion to bronchus fistula” on imaging. In the present report, we not only demonstrate a fistulous communication between the tumor and the bronchial tree, but also suggest certain technical modifications and postprocessing maneuvers, which may enable an unequivocal depiction of such fistulas, to the benefit of our surgical colleagues.

CASE REPORT

A 35-year-old male with intractable cough for the preceding year associated with recurrent hemoptysis was referred for CT scan of the thorax. The patient had been on antitubercular therapy in another hospital for 6 months with no response. On careful interrogation, the patient complained of expectoration of “fine white hairy material” in his sputum, that was presumed by us to be organized mucus. The patient however insisted that it was “hair” and not “anything else.” A contrast-enhanced CT scan of the thorax was done as per standard protocol, which revealed a rounded, well-defined, but heterogeneous mass adjacent to the lower lobe of the left lung. The lesion was epicentered at the anterior mediastinum and was closed abutting the heart and pericardium (though no invasion of these structures was suspected). The lesion had a definable wall with a mixed density core having certain enhancing areas interspersed with few foci of “fat attenuation” and that of “calcific attenuation” [Figure 1a]. This raised the suspicion of a teratoma. In addition, air was seen inside the lesion, confirming a broncho-pulmonary communication [Figure 1b]. The mediastinal pleura was displaced laterally at most sites with the anterior mediastinal fat surrounding the lesion on all aspects, associated atelectasis of left lower lobe was seen. These features confirmed our suspicion of an anterior mediastinal cystic teratoma with communication to left lower lobe bronchus. Coronal and sagittal thick maximum intensity projection (MIP) images demonstrated a fine communication between the lesion and the lower lobe bronchus [Figure 1c and d]. Additional scans were taken with an inferior gantry tilt of 12˚ (i.e. the angle of sweep of the left lower lobe bronchus in coronal plane reconstruction), oblique coronal reconstructions of the scans so achieved depicted the ‘lesion to bronchus (third order tertiary bronchus)’ communication unequivocally [Figure 2]. Further, the scanning was done in an expiratory phase to decrease the pressure gradient between the mass and the lung and hence that the mucosal flap overlying the communication opens up and becomes easily demonstrable. Surgery was planned via a left lateral thoracotomy, a pleural repair however preceded the excision of mass, in order to prevent inadvertent pulmonary hyperinflation through the fistula. This would have caused a difficulty in intraoperative ventilation as well as manipulation of lesion and was made possible only by an unequivocal demonstration of the site of the fistula. The histopathology confirmed the diagnosis of cystic teratoma with occasional immature endodermal glands interspersed with primordial hair follicles and fat/fascia lining the cyst wall [Figure 3]. The patient was discharged on postoperative day-6 with an uneventful course thereafter.

Figure 1

(a) Plain Chest radiograph showing an anterior mediastinal mass silhouetting the cardio-mediastinal outline.(b-d) Contrast enhanced computed tomography thorax shows the anterior mediastinal lesion, note the mixed density core having solid enhancing areas with few foci of “fat and calcific attenuation” (open arrow) and air seen inside the lesion (straight arrow). On initial scanning without any gantry tilt an oblique sagittal reconstruction best demonstrated the fine communication between the lesion and the lower lobe bronchus (curved arrow)

Figure 2

Oblique coronal reconstructions of additional scans taken with gantry tilt (12° caudal), provides a more accurate and convincing depiction of the ‘lesion to bronchus (third order tertiary bronchus)’ communication

Figure 3

H and E stained sections seen in low power field show features as numbered; 1-stratified squamous epithelium, 2-hair follicle, 3-sebaceous gland. Apart from these multiple small airway lined by respiratory epithelium come in the section (straight arrows)

DISCUSSION

Unruptured moderately sized mediastinal teratomas are usually asymptomatic, with the symptoms arising only when these lesions are big enough to cause mass effect.[4] The most common thoracic location of teratomas is that in anterior mediastinum, hence the ruptured lesions usually open up to the local fat planes.[45] Occasionally an odd lesion may erode across the mesothelial barrier toward the lung and hence the trachea-bronchial tree.[5] Communication with the trachea-bronchial tree gives rise to hemoptysis and trichoptysis, whereas intrapulmonary invasion presents with chest pain, dyspnea, cough and fever.[5] Without prior knowledge of presence of mediastinal teratoma, symptoms of Chronic cough and hemoptysis may often be misleading, as in our patient who was on antitubercular therapy for 6 months without amelioration of symptoms. CT scan is the modality of choice for evaluation of mediastinal masses, with the features of an unruptured teratoma being well established (1-5), these primarily consist of a mass containing tissues of varied attenuation (fat, soft tissue and calcification). On rupture (into lung) the lesion would further become heterogenous with changes of the internal architecture; the tumor margin becomes irregular, and the fat component takes a stellate configuration from a more spherical one.[56] Tracheo-bronchial invasion leads to consolidation in distal lung with visualization of air bubbles in the mass.[6] Direct communication of the mass with the airway is however difficult to demonstrate in most cases, even with the most advanced scanners.[7] This may probably be due to the fact that the pressure within the teratoma after rupture becomes much less as compared to the intrapulmonary pressure, hence causing closure of the flap covering the rent in the wall of the airway. The use of oblique plane, in addition to expiratory phase scanning, enabled us to visualize and target the point of communication between the mass and the bronchial tree. This helped the surgeon to attain a closure of the rent prior to excision of the mass. Further, thick MIP multiplannar reconstructional images maybe more appropriate in demonstrating the lesion, than just axial plane images. Such modification of the scanning technique has not been described previously but proved to be of definite importance in the present case. Trichoptysis is a rare but diagnostically conclusive symptom as far as clinical evaluation of the patient is concerned. Apart from confirming the diagnosis, CT scan with the described technical modifications can help plan the surgical protocol prospectively. Further, with the advent of newer endobronchial interventional techniques, such focused demonstration of the point of communication between the mass and lesion can prove to be helpful in a successful expedition of minimally invasive therapy.[8]