2021, Volume 37, Number 1, Page(s) 089-091
Pulmonary Acantholytic Squamous Cell Carcinoma Mimicking Lepidic Pattern Adenocarcinoma
Rukiye YILMAZ, Recep BEDİR
Recep Tayyip Erdoğan University School of Medicine, Department of Pathology, RIZE, TURKEY
An 84-year-old male patient with a history of smoking
and recent pneumonia symptoms of fever, difficulty in
breathing, and weakness presented to the chest disease
clinic. The patient had a left-sided suspicious lung mass
on his chest X-Ray (CXR). Written informed consent was
obtained from the patient. Chest computed tomography
(CT) revealed a mass of 3x2 cm on the superior lobe of the
left lung (Figure 1). CT-guided transthoracic tru-cut biopsy
of the chest was performed.
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|Figure 1: CT revealed a mass of 3x2 cm on the superior lobe of the
left lung (yellow arrow).
Microscopic examination revealed an infiltrative tumor
consisting of atypical epithelial cells with a large hyperchromatic
nucleus and showing prominent pleomorphism
and acantholytic changes with gland-like structures in the
lung parenchyma (Figure 2A,B). Immunohistochemical
evaluation revealed diffuse positive staining with p40 and
cytokeratin (CK) 7 (Figure 3A,B) while TTF-1, GATA-3
and CK20 were negative in the neoplastic cells. GATA-3
and CK20 immunohistochemical staining was performed
as the tumor contained some urothelial carcinoma-like
areas. Urothelial carcinoma metastasis was eliminated from
the differential diagnosis as these markers were negative.
A diagnosis of adenocarcinoma was eliminated and a
diagnosis of squamous cell carcinoma was supported as a
result of the negative staining with TTF-1 and diffuse strong
positive staining with p40. With these findings, the case
was reported as squamous cell carcinoma (acantholytic/
adenoid-like variant). An irregular bordered pathological
lesion (SUVmax:10.4), with an axial long border of
about 3 cm, and creating traction on the mediastinal and
costal pleura, was observed in the anterior segment of
the superior lobe of the left lung. There was no evidence
to suggest non-pulmonary SCC in other organs in the
clinical or radiological signs. The patient was considered
to be inoperable because of the distant metastases and
chemotherapy treatment was planned.
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|Figure 2: A-B) Atypical epithelial cells with large hyperchromatic and pleomorphic nucleus, showing
acantholytic changes and forming gland-like structures (H&E; x400).
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|Figure 3: Neoplastic cells showed diffuse positivity for A) CK7 (IHC; x200) and B) p40 (IHC; x200)
SCC of the lung is a histological type of non-small cell lung
carcinoma. It is one of the most prevalent lung cancers and
originates from the bronchi. SCC infrequently presents with
acantholysis, which is characterized by loosening of the cellto-
cell connection. Acantholytic SCC is a rare variant, and
arises most commonly in the skin. The acantholytic variant
of SCC is rarely seen in the skin and also has an extremely rare presentation in the lung with only a few cases reported
in the literature. Since the artefactual clefts of the tumoral
cells could resemble acantholysis and glandular lumens
or a vascular structure, acantholytic SCC is also called as
adenoid / pseudovascular / pseudovascular adenoid SCC
1-3. We aimed to report our case as it is very rare in the
Acantholytic SCC comprises 2-4% of all cutaneous SCCs.
Many skin pathology textbooks histologically characterize
SCC as adenoid (pseudoglandular) or pseudoacinar nests
with central acantholysis and cohesive peripheral tumor
cells. The skin is the most frequent site of acantholytic
tumors, with common skin pathology references.
Pulmonary acantholytic SCC results in an aggressive
clinical course, with marked lymphatic metastases 4,5. p40
has high immunohistochemical sensitivity and specificity
to distinguish lung adenocarcinoma and SCC and appears
to be an excellent marker for SCC. p40 immunostaining
should be performed routinely for the diagnosis of
pulmonary SCC 6. The positive expression rates of TTF-
1 and NapsinA are higher in lung adenocarcinoma, and
TTF-1 is highly specific and sensitive in the diagnosis of
adenocarcinoma. NapsinA may be used to distinguish
ADC and SCC 7.
In conclusion, the acantholytic/adenoid-like variant of
SCC should be kept in mind during evaluation of lung
biopsies, and careful microscopic examination and
immunohistochemical evaluation should be performed since the tumor can mimic the lepidic pattern and other
adenocarcinomas. The immunoexpression profile of SCC
can help in making the correct diagnosis.
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