대한흉부영상의학회 Korean Society of Thoracic Radiology

Discussion

Diagnosis With Brief Discussion

Diagnosis

Placental Transmogrification

Radiologic Findings

Figs 1. Chest PA shows irregular opacity at medial side of right mid to lower lung fields.
Fig 2-3. chest CT scan shows about 4 cm irregular part-solid mass with cystic component in the RLL posterobasal segment.
Figs 4-5. There was no significant interval change on low-dose chest CT scan taken 6 months later.
Right lower lobectomy was done and placental mogrification was pathologically confirmed.

Brief Review

Placental transmogrification of the lung, or pulmonary placental transmogrification, is also referred to as placentoid bullous lesion. It is known to be a very rare disease with less than 30 adequately documented cases. Clinically, placental transmogrification usually occurs in men between 20 to 50 years old; however, our case was even a more rare case due to the occurrence in a female patient. It may be asymptomatic or perhaps associated with pneumothorax or chronic obstructive lung disease.
The etiology and pathogenesis still remain unclear. It may be congenital, but no placental transmogrification has been reported in children. Placental transmogrification is not only associated with cystic or emphysematous lung lesion, but also with pulmonary fibrochondromatoushamartomas and pulmonary lipomatosis. Thus, the radiologic presentation can be bullous change or pulmonary lung nodules.
Previous articles had classified the radiologic findings into 3 patterns. The most common manifestation is bullous emphysema pattern. Next, the disease is expressed on radiography with a mixed pattern of thin-walled cystic lesion and nodule. Rarely, the radiologic finding shows a solitary nodule pattern. The disease itself is a rare disease entity, and our case had even more unusual findings of both giant bulla and subsegmental consolidation patterns.
Radiologically, differential diagnosis of the lesion includes cystic or bullous lung disease, such as bullous emphysema, particularly giant bullous emphysema (vanishing lung syndrome), and solitary pulmonary lung nodules, such as hamartoma.
Bullous emphysema shows similar imaging characteristics to placental transmogrification. Placental transmogrification usually has a unilateral giant bullous change. However, bullous emphysema generally demonstrates a diffuse bilateral lung involvement. In addition, although bullous emphysema can have rapid progression of lung parenchyma destruction in drug abuse, acquired immune deficiency syndrome or autoimmune disease, it commonly affects old age with a history of smoking and alpha-1 antitrypsin deficiency and develops over a long period of time. In particular, giant bullous emphysema is also referred to as primary bullous emphysema or vanishing lung syndrome, which is characterized by bulla occupying at least one third of the hemithorax. It may most closely resemble the image characteristics similar to placental transmogrification.
Other radiologic findings of placental transmogrification are emphysema with pulmonary nodules or solitary pulmonary nodule patterns. In rare cases, these solid pulmonary nodules contain air and fat. The radiologic differential diagnosis of the nodule includes pulmonary hamartoma. However, the image finding alone has limited value to differentiate the lesion from placental transmogrification. Therefore, making the diagnosis requires the confirmation of pathology.
In summary, the image finding of placental transmogrification presents unilateral large bullous emphysema with or without an associated nodule or consolidation. From a clinical standpoint, making an accurate preoperative diagnosis is difficult. Although it is an extremely rare disease, it must be ruled out in patients with unilateral bullous lesion who do not have high risk of bullous emphysema.

References

1. Hochhegger B, et al. Placental Transmogrification of the Lung. Lung2015;193.5:855

Keywords

Lung, Neoplasm_benign,