Teaching Case

A previously healthy 15-year-old boy presented to the emergency department with 5 weeks history of productive cough, mild grade pyrexia and shortness of breath.
Blood biochemistry results revealed deranged clotting and raised C-reactive protein, hence the patient underwent a CT examination of the chest and abdomen.

Fig 1: Chest radiograph was initially performed at presentation. This demonstrates a large left sided pneumothorax. The left hilum is bulky but no discrete area of consolidation is seen in the current radiograph.
Fig 2: Selected axial image of CT examination of the chest in soft window performed after insertion of chest drain demonstrating mediastinal lymphadenopathy and left hilar mass. The left sided pneumothorax was drained as the patient was symptomatic.
Fig 3: Selected axial image of CT examination of the abdomen showing peripancreatic low attenuation collection, which was proven to represent lymphangioma on histology.

Background:

Primary lung cancer in the paediatric population is extremely rare. In the literature, the majority of paediatric lung cancers (83.3 %), were secondary malignant lesions, whereas the primary benign and malignant cases represented 9.8% and 6.9 % respectively. [1]
The commonest presenting symptoms are: weight loss, chronic cough, and haemoptysis.

In children, 0.16% of all lung cancers occur in the first decade of life and 0.7% in the second decade. [8] Reported cases of paediatric lung carcinoma are most commonly undifferentiated carcinoma as in this case. [1] Survival in adolescents is associated primarily with stage, but is independent of histologic type or degree of differentiation, smoking history, sex, and age. [9] The chemotherapy treatment for lung cancer in childhood as in our case is based on the experience with adults. The patient described in this case remains in remission (May 2014).

Our patient had an incidental peri-pancreatic lymphangioma. With respect to this type of lesion, the anatomic regions most commonly involved are the neck and the axilla (95% of cases). [2] Abdominal lymphangiomas are very rare and represent less than 1% of all lymphangiomas. [3] They are mostly considered to be related to congenital malformation. [5] A second theory suggests secondary cases as a complication from trauma, radiation etc. [4] Several potential complications include: anaemia, pain, haemorrhage, nausea, hydronephrosis, infection and rupture.


Clinical perspective:

Pneumothorax is a rare feature of malignant lung cancer. It is frequently associated with an advanced stage of cancer. [6] In a Japanese study [7], among 180 adult patients presenting with pneumothoraces, only eight had lung cancer. Pohl et al quote a figure of 2 % of spontaneous pneumothoraces being associated with malignancy, regardless of whether it is primary or secondary. [8]

The exact mechanism for the pneumothorax being the presenting feature is not entirely understood. In our case we presume that pneumothorax resulted from air trapping in the partially obstructed left lower lobe leading to rupture of the alveoli. In the literature, suggested explanations include: extension of the tumour into the pleura and expanded alveoli rupturing into the pleural space.

Imaging perspective:

Based upon the initial CXR, spontaneous pneumothorax was considered. However, the lymphadenopathy subsequently found on the CT raised the possibility of lymphoma (far more common in children than lung carcinoma). The cystic lesion around the pancreas remained unexplained. Hence, two independent diagnoses were suspected and subsequently the patient had biopsies from the abdominal lesion as well as the bronchial mass.

Take home messages:

"Review areas" must be assessed on all CXRs presented for reporting.

In this patient, histology from both lesions was warranted to exclude the possible metastatic spread in this rare paediatric tumour.