Multifocal Chest Wall Hamartoma: A Rare Congenital Anomaly
A month old female infant presented with chest wall swelling, deformity, cough and breathing difficulty. At 23 weeks of gestation the same foetus was diagnosed on routine antenatal ultrasound having a complex mass in left hemi thorax (figure 1). Differential diagnosis of teratoma, adenomatoid malformation or complex chest wall mass was kept. Laboratory investigations revealed mild anaemia and mildly altered liver function tests. The differential counts were normal. She was referred to the Department of Radio Diagnosis and Imaging for further investigations. Chest radiograph revealed multiple expansile lesions arising from contiguous ribs causing narrowing and compromise of thoracic cavity (figure 2A). The lesions show heterogeneous appearance with areas of ground glass density and foci of speckled calcification. Plain and contrast enhanced CT of thorax was performed. Coronal and sagittal reformat and 3D reconstruction images were obtained (figure 3A & 4A). It revealed a large, heterogeneous expansile rib lesions arising from left 4th and 5th ribs with large intrathoracic component resulting in compression of left lung. There are widening of 4th and 5th intercostal spaces and shift of mediastinum towards right side. Another lesion was noted arising from anterior ends of 3rd to 5th ribs. Similar characteristic lesions of small sizes were noted in transverse process of C7 vertebra, posterior ends of left 1st and 3rd ribs and right 1st rib. Few lesions caused gross expansion and cortical thinning forming large masses with large intrathoracic components severely compromising the thoracic cavity and causing chest wall deformity. The matrix of the lesion showed insignificantly enhanced soft tissue attenuation, low attenuation cystic areas and chondroid mineralization. Based on imaging findings, differential diagnosis of multiple fibrous dysplasia or mesenchymal hamartomas was considered. Histopathology revealed that the sections chiefly consisted of spindle shaped fibroblast admixed with cartilaginous and bony tissue with evidence of endochondral ossification, suggestive of chondro mesenchymal hamartoma (figure 5). Surgical excision of the large lesions is planned based on imaging characteristics and respiratory symptoms. Excision of left 4th and 5th ribs was performed which was associated with large masses. Surgical excision and biopsy of largest lesion revealed a grossly well encapsulated greyish brown nodular hard tissue structure attached to the ribs. The cut surface was partly solid partly cystic, whitish areas (cartilage) with haemorrhagic areas were seen. The surgery was successful. At 3-month and 6-month follow up, the patient was asymptomatic and had not experienced any episodes of respiratory symptoms. The lesions which were excised did not show recurrence and the lesions which were left does not show any increase in size (figure 2B, 3B & 4B).