Basaloid Squamous Cell Carcinoma of the Lung: Two Case Reports with CT Imaging Findings

Abstract

Basaloid squamous cell carcinoma of the lung is now considered a subtype of squamous cell carcinoma as per the 2015 WHO classification and remains a relatively unknown type of lung cancer due to its rarity. Here we report two cases of basaloid squamous cell carcinoma of the lung and their CT findings to clarify some of the radiologic features of this type of cancer. Two patients aged 85 and 68 years with lung basaloid squamous cell carcinoma visited our institution and underwent surgical resection. On CT, the lesions were 3.1 and 2.8 cm in size, respectively, well-defined, round in shape with lobulated margins and prominent intratumoral necrosis. The latter case was followed after operation for 20 months, and there was no recurrence of the disease on CT. Although very rare, basaloid squamous cell carcinoma should be considered a subtype of lung cancer in tumors sharing these CT findings.

CT findings of basaloid squamous cell carcinoma of the lung in 12 patients

“…As this growth pattern of cells gradually narrows rather than completely blocks the bronchi, we think that it may cause less necrosis compared to other bronchial origin tumors. In correlation with our study, previous literature reporting basaloid SCCs, most of tumors have exhibited nodular or mass lesions without cavity formation [3,6–9] . Yamada et al [19] have reported an unusual case of basaloid SCC with cavity that showed coagulative necrotic foci of pre-existing alveolar wall in the cancer cavity junction.…”

“…The theory is as follows: adenocarcinoma cells initially develop in alveolar wall and grow toward bronchiole, and next formed a unidirectional check-valve owing to lack of cartilage in bronchiole; the accumulations of gases enter alveoli; the alveoli rupture and fuse into cavity with separation; and finally, the cavity gradually gets larger and larger with the increased inner pressure [20] . We think that the same principle can explain a case of thin walled cavity shown in case report of Kim et al [7] that was mentioned above.…”

“…We found 3 reports of 4 patients regarding image findings in the English-literature of basaloid SCCs of the lung. [ 6 – 9 ] Most of these reports, like our study, showed solitary tumor with mild to moderate enhancement with either central or peripheral location on CT. Kim et al, [ 7 ] have reported 2 cases that showed prominent internal necrosis of the tumor and 1 case showed thin walled cavitation of the tumor. However, none of the case in our study showed cavitation of the tumor.…”

“…In correlation with our study, previous literature reporting basaloid SCCs, most of tumors have exhibited nodular or mass lesions without cavity formation. [3,[6][7][8][9] Yamada et al [19] have reported an unusual case of basaloid SCC with cavity that showed coagulative necrotic foci of pre-existing alveolar wall in the cancer cavity junction. They assumed that this might have occurred in the same way as that cavities were created in rare cases in adenocarcinoma.…”

Comparison of CT findings between basaloid squamous cell carcinoma and non-basaloid squamous cell carcinoma of the lung

“…However, imaging ndings on basaloid SCC of the lung remain largely unreported. In 2020, one of our authors reported CT ndings of two cases of basaloid SCC, where tumors appeared as well-de ned round, lobulated lesion with prominent intratumor necrosis, with one case showing cavitation [12].…”