[Placentoid malformation of the lung]

Area of Science:

• Pulmonary Pathology
• Surgical Pathology
• Congenital Malformations

Background:

• Differential diagnosis of bullous and cystiform lung alterations includes rare cystic tumors and congenital malformations.
• Localized unilateral emphysema can present with complex clinical pictures requiring surgical intervention.

Observation:

• A rare case presented with clinical diagnosis of localized unilateral emphysema leading to bullectomies and pneumonectomy.
• Macroscopic examination revealed spongiform solid areas and physaliform transformation, histomorphologically resembling placentalike formations.
• Histology showed 'villous stroma' with regressive alterations, fatty islets, and leiomyomatous areas.

Findings:

• The lesion, termed "placentoid malformation," has a pathognomonic histological appearance.
• Pathogenesis remains unclear; results contradict the hypothesis of development from pre-existing lung emphysema.
• Evidence suggests an independent lesion, possibly a congenital hamartous malformation with self-developing progression.

Implications:

• Emphysematous alterations may result from a valve mechanism due to traction forces.
• Lymphatic pathways in border areas might play a significant etiological role.
• This case expands the understanding of rare lung malformations and their potential origins.