Clinical Summary:

The patient presented to her pediatrician at five months of age with fever, tachypnea and labored respiration. She was diagnosed with Influenza B and admitted to the hospital. She had been born at term with an uneventful neonatal course. She had no significant illnesses prior to admission although her mother stated that her breathing had not been "normal" for some time. Her family history was notable for B-cell leukemia in the mother. A chest X-ray on admission showed hyperaeration of the left lung. A CT scan was performed and showed a markedly emphysematous left upper lobe with compressive atelectasis of the left lower lobe and mediastinal shift. There were multiple fine septations in the hyperinflated lobe with no visible normal lung tissue. The radiographic differential diagnosis included congenital cystic pulmonary airway malformation (formerly called cystic adenomatoid malformation) and congenital lobar emphysema. The patient recovered from her upper respiratory infection and returned approximately 3 weeks later for resection of the abnormal left upper lobe. At surgery, the left upper lobe showed massive overinflation with attenuation of the visceral pleura. The upper lobe was dissected off the lower lobe with ligation of upper lobe branches of the pulmonary vascular structures and the left upper lobe bronchus. No other cystic abnormalities involving the pleura, mediastinum or left lower lobe were noted.

Gross examination of the 11 x 7 x 1.3 cm left upper lobe showed a 6.5 cm diameter bulla in the apex. Sections showed a wall thickness of 0.2 cm and multiple incomplete fibrous septae consistent with collapsed cysts ranging from 1.0 to 2.0 cm in diameter. There was approximately 1 cm3 of brown fluid within the bulla. The uninvolved parenchyma showed atelectasis and consolidation. Microscopic sections showed a pleural-based cystic lesion. The cyst walls were variably cellular and lined by either benign mesothelium or benign epithelium. Sections of cyst walls showed focal condensations of primitive stellate, round and spindle-shaped cells beneath the cyst lining cells imparting a cambium layer appearance. These cells showed nuclear hyperchromatism, high nuclear-to-cytoplasmic ratios and were mitotically active. Loose fibrovascular tissue containing spindle-shaped cells resembling fibroblasts predominated in the deeper portions of the septae. Small nodules of primitive cartilage were also seen in the cyst walls focally. The lesion did not involve the margins of excision. The pathologic diagnosis was made. A full body CT scan and head MR showed no evidence of metastatic disease. However, a hypodense lesion in the lower pole of the left kidney was noted. A renal ultrasound determined this to be a simple cyst.

The patient was then followed with serial chest X-rays and CTs. At 4 months post-surgery a CT scan identified 3 parenchymal cysts in the remaining left lung ranging from 0.24 to 0.62 cm in diameter, which in retrospect were there 1 month post-surgery, and 2 cysts in the left kidney. At 6 months post-surgery CT scans showed 4 distinct cystic lesions in the left lung ranging from 0.27 to 2.1 cm in diameter, and 2 distinct cystic lesions in the right lung measuring 0.24 and 0.57 cm. The left kidney contained 3 distinct cysts measuring 1.9 cm in maximum dimension. The patient was taken to the operating room where a left partial nephrectomy and wedge resections of the left lower lobe lung cysts were performed.

Gross examination of the kidney showed a subcapsular multiloculated cyst measuring 1 cm in maximum dimension. Microscopic examination of the kidney showed a multilocular cyst lined by bland, flattened cuboidal epithelium. The cyst walls contained loosely arranged primitive mesenchymal cells with a stellate configuration in a myxoid background. No cambium layer was seen. Within the parenchyma adjacent to the cysts, rare abortive glomeruli and dilated, irregular tubules were seen similar to that seen in embryologic renal dysplasia. No blastema or cartilage was present. Grossly, the wedge biopsies of lung showed subpleural, thin-walled multiloculated cysts measuring 1.2 and 1.5 cm in greatest dimension. Microscopically the cysts had a similar architecture to the previous left upper lobe specimen. There were subepithelial condensations of spindle cells showing rare mitotic activity. No cartilage was present. Focally, the subepithelial spindle cells contained abundant pink cytoplasm suggestive of rhabdomyoblastic differentiation. These cells were desmin positive.

Clinical Summary:

A 17-year-old Caucasian male presented to his local primary care physician with a complaint of right thigh pain that had recently increased in intensity. The pain was deep seated and would awaken him from his sleep. He had been using over the counter nonsteroidal anti-inflammatory medications to lessen the pain. He also expressed concern about a tender mass that he had first noticed about 6 months previously. It had recently increased in size. With further questioning by the primary care physician, the adolescent related that the onset of the discomfort began about 2 years ago following a knee sprain during a high school football game. Treatment had not been sought for this injury.