M1: Distant metastasis present; or separate tumor
nodules in the ipsilateral nonprimary-tumor lobes of the lung. Separate tumor nodules in
the contralateral lung are considered M1 if they are of the same histologic cell type as
the primary lesion. A contralateral lung tumor with a different cell type is considered a
synchronous primary lesion and should be staged independently (verbal communication
Clifton F. Mountain, MD, Division of Cardiothoracic Surgery, The University of California
Medical Center at San Diego).
Example 1: The patient in this example had an
adenocarcinoma in the left upper lobe (right image). A separate lesion was identified in
the superior segment of the left lower lobe (yellow arrows). The lesion lacked definitive
mass-like characteristics and was referred to as an "infiltrate" by the
interpreting radiologist. During surgery, the lesion in the superior segment of the left
lower lobe was palpable, so it was removed and discovered to be bronchogenic carcinoma-
final histologic subtype was adenocarcinoma. This is an example of a stelite nodule in the
ipsilateral non-tumor lobe-- classified as a T4 lesion (previously M1).
NOTE: To load a higher resolution
view, simply click directly on the image below.
Example 2: The case below demonstrates a large right lower
lobe adenocarcinoma (T). An ill-defined pleural based density was noted in the posterior
left lower lobe (yellow arrow). The patient required accurate staging prior to entry into
protocol, so the lesion in the left lung was resected thoracoscopicly. Histologic analysis
of the left lung lesion revealed metastatic bronchogenic adenocarinoma-- this is an M1a
lesion.
NOTE: To load a higher resolution
view, simply click directly on the image below. Other examples of metastatic disease can be found in the chapter
on CT in the staging of bronchogenic carcinoma.
