Knowing the unknown in oral squamous cell carcinoma: An observational study

Introduction

Conventional oral squamous cell carcinoma (OSCC) is relatively easy to diagnose on histopathology, as it comprises dysplastic epithelial cells with variable degrees of squamous differentiation. Different grading systems have been employed in grading OSCC based on its dysplastic features and host response. Some unusual features such as clear cell change, epithelial-mesenchymal transition (EMT), stromal hyalinization, stromal desmoplasia, perineural invasion, vascular invasion, tissue eosinophilia, giant cells, and tertiary lymphoid follicle formation are evident in OSCC histologically but have not yet been accounted in any grading systems of OSCC except perineural and vascular invasion.

Aim

The aim of the present study was to identify these uncommon features and to correlate them with different grades of OSCC.Materials and Methods:This study was conducted on 100 histopathologically confirmed OSCC cases retrieved from the archives of our department. They were graded on the basis of Broder's grading system and were reviewed for the features mentioned above. Data collected were subjected to statistical analysis.

Results

Clear cell change, EMT, foreign body giant cells, and tumor giant cells were observed in 13%, 20%, 1%, and 3% of cases, respectively. We found stromal desmoplasia in 15% and stromal hyalinization in 9% of cases. Tissue eosinophilia, tertiary lymphoid follicle formation, and perineural invasion were observed in 12%, 3%, and 2% of cases, respectively. Vascular invasion was not evident in any of the cases examined.

Conclusion

The incidence of the unusual features was 7.8% in our study.

Colon adenoma and adenocarcinoma with clear cell components - two case reports

Background

Diagnoses reflect clear cell morphologies when tumor cells have clear cytoplasm in many organs, and the nature of such clear cells is typically identified. Colorectal tubular adenoma or adenocarcinoma, conversely, rarely show clear cells, the reason for which remains uncertain. We report 2 colon tumors with clear cell components (Case 1: adenoma; Case 2: adenocarcinoma) and investigate the nature of the clear cells.

Case presentation

Case 1 was a 75-year-old man with a superficial elevated polyp detected in the rectum for whom endoscopic submucosal dissection was performed. Microscopically, 10% of the tumor showed dysplastic columnar epithelium with clear cytoplasm forming tubular structures accompanied by conventional tubular adenoma. Case 2 was a 58-year-old man with a pedunculated polyp found in his sigmoid colon for which polypectomy was performed. Microscopically, 90% of the tumor showed dysplastic columnar epithelium with clear cytoplasm forming fused glands or cribriform structures adjacent to the ordinal tubular adenocarcinoma. In both cases, clear and ordinary tumor cells were negative for CK7 and positive for CK20 and CDX2, consistent with findings of colorectal origin. Different results were found for CEA and CD10 staining. CEA was positive on the luminal side of the conventional area in contrast diffuse cytoplasmic staining of the clear cell area in both cases. CD10 was only positive for the clear cell component of case 2. The clear cell components were negative for Periodic acid-Schiff (PAS), Alcian blue, and mucicarmine staining and AFP immunohistochemistry. An ultrastructural examination found multiple cytoplasmic lipid-like vacuoles in the clear cell component that were predominantly negative for adipophilin by immunoelectron microscopy.

Conclusions

We investigated tubular adenoma and tubular adenocarcinoma with clear cell components. The accompanying conventional tubular adenoma or adenocarcinoma cells helped us to evaluate the atypia of the clear cells. Diffuse cytoplasmic staining of CEA and CD10 suggested that the clear cell component might harbor malignant potential. We were unable to verify the well-known causes of clear cytoplasm, such as an accumulation of glycogen, lipid, or mucin and enteroblastic differentiation. The causes of clear cells in the colorectal region remain uncertain; however, possible explanations include autolysis and carbohydrate elution.

Clear cell change in a lower lip mucocele

Oral mucocele is a common reactive lesion of the oral mucosa, which microscopically exhibits mucus extravasation surrounded by a wall of granulation tissue containing abundant foamy macrophages. Unusual variants, such as superficial mucoceles, mucoceles with myxoglobulosis-like change and mucoceles with synovial metaplasia-like change have been reported. We report a 74-year-old man who presented an asymptomatic translucent swelling on the lower labial mucosa diagnosed as mucocele showing a macrophage proliferation with extensive clear cytoplasmic vacuolation and signet-ring formation. This unusual presentation expands the microscopic spectrum of the oral mucoceles and can eventually lead to differential diagnosis with primary or metastatic clear cell neoplasms. In these cases, relevant clinical information, histochemistry and especially immunohistochemistry, are helpful for arriving at an accurate diagnosis.