Adenocarcinoma in situ of lung

Case contributed by Melbourne Uni Radiology Masters



Patient Data

Age: 74-year-old
Gender: Female

CT Chest

This is the initial CT showing a 5mm nodule with surrounding ground glass opacification, the total dimensions are approx. 18mm x 15mm  in the left upper lobe.

The lungs were otherwise clear.

The mediastinum and pleural spaces were normal


CT Chest (one year later)

This is a follow up CT study in this patient.

The left upper lobe nodule and the surrounding ground glass alveolar opacification has not significantly changed and appearances are suspicious for an adenocarcinoma in situ.

MICROSCOPIC DESCRIPTION: 1. Sections of the lung show features of a moderately differentiated adenocarcinoma. It is 18mm in size. The tumour forms acinar structures (100%). The periphery shows lepidic pattern of spread for 1-2mm. The tumour cells have enlarged nuclei, prominent nucleoli and moderate amounts of eosinophilic cytoplasm. The tumour extends close to but not through the elastic layer of the visceral pleura. No evidence of lymphovascular invasion is seen. The tumour is completely excised. The tumour cells are TTF-1 positive. 2. Sections of the completion lobectomy show no residual tumour. The bronchial and vascular resection margins are uninvolved. 3 normal hilar lymph nodes are seen. The lung parenchyma is unremarkable. 3. 2 lymph nodes are identified with no evidence of tumour. 4. 1 lymph node is identified with no evidence of tumour. 5. 1 lymph node is identified with no evidence of tumour.

DIAGNOSIS: 1. Left upper lobe: Moderately differentiated adenocarcinoma. -18mm in maximum dimension. -No evidence of pleural invasion. -No evidence of lymphovascular invasion. -Tumour completely excised. 2. Left upper completion lobectomy: -No residual tumour seen. -Bronchial resection margin clear. -3 normal hilar lymph nodes present. 3. Hilar lymph node: 2 lymph nodes identified with no evidence of tumour. 4. Station 5: 1 lymph node identified with no evidence of tumour. 5. Station 11: 1 lymph node identified with no evidence of tumour.

Case Discussion

The ground glass halo around a nodule suggests the involvement of the adjacent alveoli or septa at a resolution too fine for our CT equipment. It could represent either fluid/hemorrhage or possible "lepidic" growth of a tumor (i.e. adenocarcinoma in situ).

A pulmonary metastasis may be surrounded by a peritumoral hemorrhage and result in a ground glass nodule. Certain metastases do this more commonly, such as:

  • melanoma
  • renal cell carcinoma
  • choriocarcinoma
  • angiosarcoma

However, the ground glass nodule is not a specific finding, and in the setting of an oncologic patient, who may be immunocompromised from chemotherapy, it is prudent to suggest a differential that includes infectious processes that have ground glass halos, such as:

  • angioinvasive aspergillosis
  • candidiasis
  • possibly, tuberculoma

Lymphoma and a lymphoproliferative process may also present with ground glass nodules/masses, another consideration in an immunocompromised patient.

Gastrointestinal adenocarcinoma metastases have been shown to have a lepidic pattern of growth. They may uncommonly present with a ground glass halo (~3%).

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Case information

rID: 38685
Published: 30th Jul 2015
Last edited: 2nd Sep 2019
System: Chest
Tag: rmh
Inclusion in quiz mode: Included

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