Pseudoangiosarcomatous squamous cell carcinoma of the lung

Atypical Histopathological Aspects of Common Types of Lung Cancer-Our Experience and Literature Review

Lung cancer is among the most common oncological diseases regarding incidence and mortality, with most of these having epithelial origins. Pathological reporting of these tumors is conducted according to the 5th edition of the World Health Organisation (WHO) classification of thoracic tumours. This study aims to draw the pathologist's attention to four rare, atypical microscopic aspects that some of the most common types of lung malignancies reveal upon standard evaluation (hematoxylin-eosin stain) that make histopathological diagnosis challenging: acantholytic, pseudoangiosarcomatous, signet ring cell, and clear cell features. Each of these aspects was exemplified by a case diagnosed in the pathology department of the "Marius Nasta" Institute. Furthermore, we analyzed the classification dynamics of different WHO editions and used PubMed to review articles written in English and published in the last eleven years on this subject. Pathologists should be familiar with these unusual aspects to avoid misdiagnoses and to ensure the correct classification of tumors, which is extremely important because these tumor phenotypes have been associated with specific molecular alterations and a worse clinical evolution. There is a need to clarify the histogenesis and associated genetic mutations, given the fact that the rarity of these tumor phenotypes makes their study difficult. Some authors consider these to be overlapping entities; however, we do not encourage this, as they may exhibit different prognoses and various molecular alterations with important therapeutic implications. The signet ring cell feature was associated with ALK rearrangement in lung adenocarcinoma; thus, these patients can benefit from tailored therapy with ALK-tyrosine kinase inhibitors (ALK-TKI). Recent studies associated clear cell morphology with FGFR3-TACC3 fusion, suggesting that patients with this diagnosis may be potentially eligible for FGFR inhibitors. We described, for the first time, the pseudoangiosarcomatous pattern in a case of lung adenocarcinoma; to our knowledge this aspect has only been described until now in the context of squamous cell carcinomas.

Pseudovascular Adenoid Squamous Cell Carcinoma of Buccal Mucosa-a Rare Aggressive Variant

Pseudo-vascular adenoid squamous cell carcinoma (PASCC) is an uncommon histological variant. It is characterized by an acantholysis of the tumor cells and the formation of anastomosing spaces and channels. It gives a false appearance of glandular differentiation mimicking angiosarcoma. PASCC has been reported in the head and neck, as well as in other organs like the breast, lungs, urinary bladder, vulva, and the uterine cervix. We report a case of PASCC of the oral cavity in a recently operated case of squamous cell carcinoma of the buccal mucosa.

Acantholytic squamous cell carcinoma of the lung with marked lymphogenous metastases and high titers of myeloperoxidase-antineutrophil cytoplasmic antibodies: a case report

BACKGROUND

Acantholytic squamous cell carcinoma (ASQCC), histologically characterized by intercellular bridge loosening, is recognized as a rare variant of squamous cell carcinoma (SQCC). ASQCC may demonstrate a worse prognosis than conventional SQCC. Pulmonary ASQCC is particularly rare; its biological behavior and prognostic data have not been reported.

CASE PRESENTATION

We report the clinical and autopsy findings of a 71-year-old Japanese man with pulmonary ASQCC. Pulmonary lesions, suggestive of idiopathic interstitial pneumonia, were radiologically observed 3 and 6 years prior to the patient's most recent hospitalization; however, the patient did not undergo further medical examinations. Upon being discovered unconscious, the patient was admitted to our hospital. Dehydration and lower limb muscle weakness were noted, as were laboratory findings of coagulation abnormalities and renal dysfunction. Computed tomography helped confirm a 21-mm peripheral nodule in the upper left lobe of the lung, with associated swollen lymph nodes in the bilateral hilar, mediastinal, and para-aortic regions. Brain and spinal lesions, suggestive of neurological disturbances, were not found. Small cell lung carcinoma was suspected, upon admission, but high serum levels of squamous cell carcinoma antigen and cytokeratin-19 fragments were present. Therefore, advanced lung cancer, possibly SQCC, was diagnosed. The patient was treated with best supportive therapy, and died one month after admission. Hypercalcemia and high serum levels of parathyroid hormone-related protein (PTHrP) and myeloperoxidase-antineutrophil cytoplasmic antibody (MPO-ANCA) titers were observed. Progressive renal insufficiency was absent due to improved renal function subsequent to hydration. An autopsy helped confirm the left lung tumor as an ASQCC associated with pulmonary lymphangitic carcinomatosis and multiple metastases in the lungs and lymph nodes. Skin lesions suggesting malignant tumors were absent. The metastatic lesions consisted largely of acantholytic tumor cells, and the lungs showed usual interstitial pneumonia pattern; vasculitis was absent.

CONCLUSIONS

This is the first reported case of pulmonary ASQCC resulting in an aggressive clinical course, with marked lymphogenous metastases and PTHrP-associated hypercalcemia. The high serum MPO-ANCA titers were clinicopathologically insignificant, but may have been related to the pulmonary interstitial lesion. Pulmonary ASQCC represents a highly malignant subset of lung cancer.