Cancer stem cells (CSCs) have the ability to self-renew and are present in most tissues including breast, brain, lung, head and neck, prostates, testis, ovary, esophagus, colon and liver. Their origin is yet to be discovered though a series of hypotheses have been proposed in this regard. CSCs play a role in not only the creation of cancer but also its evolution, metastasis and recurrence. CSCs have an important role in cancer therapy and the resistance toward chemotherapeutic agents. This article reviews the characteristics of CSCs in terms of origin, methods of isolation and cancer therapy.

The objective of this review is to introduce Merkel cells (MCs), to provide a basic overview on the theoretical background of function, development and clinical importance of MCs. The origin of human MCs have been controversial. Some investigators believe that it is a neural crest derivate, whereas others have proposed that it is a differentiation product of the fetal epidermal keratinocytes. MCs are cells primarily localized in the epidermal basal layer of vertebrates and concentrated in touch-sensitive areas in glabrous, hairy skin and in some mucosa. In routine light microscopy, human MCs can hardly be identified. Cytokeratin 20 (CK20) is a reliable marker with highest degree of specificity. MCs can be also distinguished by electron microscopy. MC carcinoma (MCC) is an uncommon and often aggressive malignancy and found mainly in elderly patients. It occurs most frequently in the head and neck region. Diagnosis is based on typical histological presentation on hematoxylin and eosin (H and E) stained slides together with the results of immunohistochemistry. Histologically, MCC has been classified into three distinct subtypes: Trabecular, intermediate and small cell type

Odontoameloblastoma (OA) is an extremely rare mixed odontogenic tumor with both epithelial and mesenchymal components. OA develops from proliferating odontogenic epithelium and mesenchymal tissue. Till date, around 20 cases have fulfilled the histologic criteria of the current World Health Organization (WHO) histologic classification of odontogenic tumors. It affects predominantly young patients with a median age of 20.12 years, and has a predilection for males and occurs in posterior segments of either jaw with slight inclination for mandible. Review of literature shows only three reported cases in the anterior mandible. Here, we report a case of OA in the anterior mandible.

Inverted papilloma is a benign epithelial growth in the underlying stroma of the nasal cavity and paranasal sinuses. The pathogenesis of this lesion remains unclear although allergy, chronic sinusitis and viral infections have been suggested as possible causes. The tumor is well known for its invasiveness, tendency to recur and association with malignancy. Recurrence rates of inverted papilloma are unacceptably high, which actually represents residual disease in most cases. In this study, we have presented a case report and reviewed the histological features of sinonasal inverted papilloma.

Salivary gland swellings can result from tumors, an inflammatory process or cysts. It can sometimes be difficult to establish; whether pathology arises from the salivary gland itself or adjacent structures. Neoplasms of the salivary glands account for less than 1% of all tumors, 3–5% of all head and neck tumors and benign pleomorphic adenoma (PA) of minor salivary glands arising de novo is very rare. PA is the most common tumor of the salivary gland. While the majority arises from the parotid gland, only a small percentage arises from the buccal minor salivary gland. A case of PA of minor salivary glands in the buccal mucosa in a 70-year-old female is discussed. It includes review of literature, clinical features, histopathology, radiological findings and treatment of the tumor; with emphasis on diagnosis.