GIANT PULMONARY HAMARTOMA Dr Smruti Hindaria

Definition A hamartoma is a mostly benign, focal malformation that resembles a neoplasm in the tissue of its origin A developmental malformation Clonal chromosomal aberrations that are acquired through somatic mutations On this basis are now considered to be neoplastic Grows at the same rate as the surrounding tissue. It is composed of tissue elements normally found at that site, but they are growing in a disorganized manner. Hamartomas occur in many different parts of the body, most often asymptomatic incidentalomas (undetected until they are found incidentally on an imaging study obtained for another reason).

Case Report A previously healthy 33-year-old lady was investigated for worsening breathlessness. Chest radiography demonstrated a mass in the left chest and a subsequent CT scan revealed a large anterior mediastinal mass extending mostly into the left hemithorax and compressing the left lung. CT guided bviopsy was s/o hamartoma. Surgical excision of this mass was indicated due to its large size.

Excision of the mass The patient underwent a left posterolateral thoracotomy A giant fibrocartilagineous tumour was found arising superficially from the medial border of the left lung occupying most of the left chest and extending to the anterior mediastinum. The mass was compressing the left lung with no evidence of local invasion. The left phrenic nerve was identified and preserved, and the tumour was found to be adherent to the medial border of the lung and was easily dissected with sharp dissection and removed en bloc.

Postoperative recovery The postoperative recovery was uneventful Patient was discharged home on the seventh postoperative day. Three months postoperatively the patient remains well. The final histology of the tumour, measuring 25.5 × 17.5 × 15.5 cm, and weighing 2200 g was a pulmonary hamartoma with predominantly adipose and cartilaginous differentiation with placental villi formation.

Discussion Most common form of benign lung tumours Incidence 0.025% – 0.3% Parenchymal lesions more common, endobronchial lesions only about 10% The peak incidence is between the sixth and seventh decades with a male preponderance

The parenchymal lesions are usually an incidental radiological finding of a round homogeneous opacity in the periphery Endobronchial lesions are usually associated with haemoptysis and obstructive pneumonia . The size of these parenchymal lesions ranges from 1–8 cm and the tumour in our case is more than 3 times that of any previously published The histology of the parenchymal lesions usually reveals a predominant chondroid differentiation (80%), with fibroblastic (12%), fatty (5%) and osseous (3%) differentiation making the rest . In our case it was predominantly made of adipose and leiomyomatous tissue with placental villi differentiation. The size of the tumour and the histology make it an unusual presentation.