Pharyngeal squamous cell carcinoma with osteoclast-like giant cells: a case report and review of the literature

This article presents a patient with nasopharyngeal squamous cell carcinoma with OLGCs. The histopathological and immunohistochemical results are discussed along with the literature on the origin, constitutional mechanisms, and clinical importance of these cells.

OLGCs may be found in various sites and in different epithelial and mesenchymal tumors. Although they are most commonly reported in breast[],[] and pancreas[] carcinomas, they can also be seen in carcinomas of the gallbladder,[] stomach,[] and urinary system,[] or stromal tumors of the uterus.[] They are extremely rare in squamous cell carcinomas[] and have never been reported in tumors in the nasopharynx.

There are two theories explaining the origin of OLGCs. The first is the transformation of malignant cells into giant cells. Studies of pancreas carcinomas suggest that OLGCs are related to precursor dysplastic ductal epithelial cells.[] Alternatively, it has been proposed that OLGCs originate from reactive stromal cells.[] Because the morphological findings, including the presence of hemosiderin and cell remains, indicate phagocytic activity, and the immunoprofile (positive for CD68, leukocyte common antigen, and Mac 387) is consistent with a monocytic/histiocytic origin, the theory suggesting that OLGCs are a subtype of macrophages is more widely accepted.

Recently, studies have examined the similarities between osteoclasts and OLGCs found in extraskeletal tumors. The two cell types cannot be distinguished from each other under light microscope. They are also similar ultrastructurally in terms of their cellular surface structures, Golgi apparatus, and lysosomes. Immunophenotypically, OLGCs contain alpha-1 antitrypsin, CD68, and acid phosphate activity, indicative of a monocyte/macrophage origin. Both cell types have the ability to resorb bone, although the activity of OLGCs is not influenced by parathormone or calcitonin levels. Based on the findings, OLGCs found in extraskeletal tumors appear to be specific macrophage subtypes different from osteoclasts and foreign-body-type giant cells.[]-[] Sakai et al.[] studied pancreas carcinomas containing OLGCs and reported that the giant cells expressed histiocytic markers and did not include the ki-ras mutation. The morphologic attributes and immunoprofiles of the giant cells found in the current patient are both suggestive of the benign, monocytic/histiocytic nature of these cells. These cells are thought to be histiocytes that had migrated into the tumor tissue as a result of chemotactic factors released from the tumor cells and that coalesced there to form giant cells. However, further studies are required to clarify the specific mechanism involved.

Squamous cell carcinomas with sarcomatous differentiation may contain multinuclear giant cells. However, the morphological and immunohistochemical characteristics of those cells differ from those of OLGCs. We considered sarcomatous differentiation of squamous cell carcinoma in the differential diagnosis of our patient's nasopharyngeal tumor, as it contained giant cells. However, the benign morphology and the expression of histiocytic markers indicated the reactive nature of the giant cells and revealed the monocytic/histiocytic origin.

Although the giant cells accompanying carcinomas belong to a different morphological spectrum, the clinical and prognostic importance of the presence of these cells is not known. Studies of breast and pancreas carcinomas, which are the most common carcinomas to present with OLGCs, indicate that these tumors have a better prognosis than typical carcinomas.[], [], [], [] However, the limited number of cases and the lack of long follow-up studies hinder the clarification of the importance of this observation. There are also contradictions regarding the identification of the tumors associated with OLGCs. Whether or not this histologic feature should be mentioned in reports remains controversial.

The presence of OLGCs may cause some difficulties in reaching a diagnosis. While in some cases it may be confused with sarcomatous transformation, in others it is difficult to discern from giant cell tumors. A detailed histomorphological examination, comprehensive immunohistochemical profile analysis, and many samples are required to discriminate such cases.

To our knowledge, the presence of OLGCs in nasopharyngeal tumors has not been reported previously in the English literature. In this case, the giant cells infiltrating the tumor were benign and had a monocytic/histiocytic origin. Studies including large case series should supply reliable information on the clinical and prognostic importance of this histological feature. Denoting the presence of OLGCs in pathology reports is important in terms of forming a database for future studies.