Among the cases with adenocarcinoma (AC) showing PD-L1 expression, a solid pattern was predominant in 5 and a lepidic pattern
was predominant in 2 cases.
A discontinuous lepidic pattern
can be seen at the periphery of the lesion, and adjacent alveolar spaces may contain mucin.
There was also a focal lepidic pattern
of growth seen at the periphery of the specimen.
(52) In some instances, tumors that metastasize or grow in the interstitium, including squamous cell carcinoma, can induce a pneumocyte reaction that can be sufficiently atypical as to raise a concern for lepidic pattern
adenocarcinoma (Figure 4, C).
The presence of STAS is an exclusion point in the diagnosis of minimally invasive adenocarcinoma (MIA), a small, solitary adenocarcinoma ([less than or equal to] 3 cm) with predominantly lepidic pattern
and invasion extending 5 mm or less.
(c) Solitary adenocarcinoma (not more than 3 cm in greatest dimension), with a predominantly lepidic pattern
and not more than 5 mm invasion in greatest dimension in any one focus.
An example of the macroscopic features of invasive lung adenocarcinoma with a lepidic pattern
. Central firm area corresponds to tumor invasion, whereas the peripheral, ill-defined area matches the lepidic pattern
If the alveolar walls are covered with tumor cells (ie, lepidic pattern
), this may be mistaken for a papillary carcinoma (2,6) (Figure 1, C and D).
As we have over the decades come to better understand lung neoplasia and preneoplasia, bronchioloalveolar carcinoma (far from being understood as a single, specific lesion as it was originally considered) has leant its appellation to 5 clinically and pathologically distinct entities, namely, 3 nonmucinous lesions (adenocarcinoma in situ, minimally invasive adenocarcinoma, and adenocarcinoma with a prominent lepidic pattern
) and 2 mucinous lesions (mucinous adenocarcinoma in situ and mucinous adenocarcinoma).
The predominant pattern seen in the EGFR-mutant-positive lung cancer group was lepidic (44%) as compared to patients with wild-type gene, whose tumors exhibited acinar pattern in 69% and lepidic pattern
in 15% of cases; P < .001 (Figure 3).
Two cases with lepidic pattern
and showing elastin in the fibrovascular cores are described.
of adenocarcinoma, characterized by noninvasive surface alveolar growth of tumor cells (hematoxylin-eosin, original magnification X200).