Lung nontumor
Other nonneoplastic disease
Pulmonary placental transmogrification

Editorial Board Member: Andrey Bychkov, M.D., Ph.D.
Editor-in-Chief: Debra Zynger, M.D.
Jian-Hua Qiao, M.D.

Topic Completed: 18 February 2019

Minor changes: 19 February 2019

Copyright: 2018-2019,, Inc.

PubMed Search: Pulmonary placental transmogrification

Jian-Hua Qiao, M.D.
Page views in 2019: 955
Page views in 2020 to date: 569
Cite this page: Qiao JH. Pulmonary placental transmogrification. website. Accessed August 7th, 2020.
Definition / general
  • Pulmonary placental transmogrification is a rare lesion, characterized by cystic lesions of the lung
  • First described in 1979 by McChesney (Lab Invest 1979;40:245)
Essential features
  • Placental transmogrification or placentoid bullous lesion of the lung is an unusual condition in which the alveoli develop a peculiar villous configuration that resembles placental villi at low microscopic magnification
  • Villous appearance probably results from the development of edema and fibrosis in the residual strands of alveolar tissue present in the enlarged airspaces of severe emphysema
  • Placental transmogrification of the lung has been described in patients with severe emphysema induced by cigarette smoking, congenital giant bullous emphysema and fibrochondromatous hamartomas of the lung
  • Pulmonary placental transmogrification, bullous emphysema, placentoid bullous lesion
ICD coding
  • ICD-10: J98.4 - Other disorders of lung
  • Usually occurs in men aged 20 - 50
  • 48% have a history of smoking
  • Lung parenchyma, usually subpleural and unilateral
  • Etiology and pathogenesis remains unclear
  • Hypotheses
    • Variant of giant bullous emphysema
    • Initial clear cell proliferation followed by emphysema-like cystic change; uncertain if proliferation is clonal (Hum Pathol 2004;35:517)
    • Congenital hamartomatous malformation
  • Can have fatty infiltration (Mod Pathol 1997;10:846)
    • May be the result of metaplastic mesenchymal differentiation
    • Occasionally, pulmonary lipomatosis is reported as a variant of placental transmogrification
Clinical features
  • Patients might be asymptomatic or present with dyspnea, chronic obstructive lung disease, pneumothorax or a combination of these
  • Chest tightness, cough and chest pain
Radiology description
Prognostic factors
  • A few patients with incomplete resection of pulmonary bullae have recurrent disease
Case reports
  • Surgical resection, including video assisted thoracoscopic surgery (VATS), pneumonectomy or lobectomy
  • Surgical resection is usually curative and leads to successful improvement of symptoms and quality of life
  • Lymph node dissection is unnecessary
Gross description
  • Resembles cystic lesions with variable amounts of intracystic papillary proliferation
  • Affected areas are replaced or filled by gelatinous tissues described as bubbly, vesicular, grape-like or sponge-like
Gross images

Images hosted on other servers:

Massively dilated bullae

Fatty infiltration

Microscopic (histologic) description
  • Bullous emphysema / cystically dilated airspaces, usually subpleural
  • Intracystic proliferation of variable sized papillary structures, which are morphologically similar to mature chorionic villi
  • Cores of papillary / villous structures contain congested capillary sized vessels
  • Papillary / villous lesions are surrounded by hyperplastic alveolar pneumocytes
  • Infiltration of mature adipocytes is sometimes identified in papillary / villous lesions
  • Pleural reactive changes are present and usually secondary to pneumothorax, including granulation proliferation, acute hemorrhage and infiltration of eosinophils
Microscopic (histologic) images

Contributed by Jian-Hua Qiao, M.D.

Foci of subpleural bullous emphysema

Clusters of mature placental chorionic villi-like structures

Images hosted on other servers:

Fatty infiltration

Gross and microscopic features

Ki67 and TTF1

Abundant mast cells in stroma

Positive stains
Negative stains
Molecular / cytogenetics description
  • Interstitial clear cells were dissected by laser capture microdissection in 2 cases, DNA of interstitial clear cells were extracted and used for studies of 19 microsatellites by PCR (polymerase chain reaction) and automatic sequencer (Hum Pathol 2004;35:517)
    • Microsatellite alterations were observed in 13 markers in case 1 and in 8 markers in case 2
    • Loss of heterozygosity (LOH) was found in 1 chromosomal region in case 1 and none of the tested regions in case 2
Differential diagnosis
Board review style question #1
Which of the following statements applies to current practice in pulmonary placental transmogrification?

  1. Complete mediastinal or hilar lymph node dissection is necessary
  2. It usually occurs in women aged 20 - 50
  3. Lesion is negative for TTF1
  4. No patients had a history of smoking
  5. Surgical resection is the treatment of choice
Board review answer #1
E. Surgical resection is usually curative and leads to successful improvement of symptoms and quality of life.

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Board review style question #2
A young man with pneumothorax and pleural blebs had a VATS lung wedge biopsy performed. Microscopic examination revealed a subpleural emphysematous lesion with the following papillary lesions in dilated airspaces. What is your diagnosis?

  1. Bronchogenic cyst
  2. Congenital cystic adenomatoid malformation
  3. Cystic non small cell lung cancer
  4. Intralobar pulmonary sequestration
  5. Pulmonary placental transmogrification
Board review answer #2
E. Pulmonary placental transmogrification. Papillary lesions are morphologically identical to mature chorionic villi of placental tissue. When these papillary / villous lesions present in dilated airspaces of resected lung, it is diagnostic for pulmonary placental transmogrification

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