Journal of Oral Science, Vol. 41, No. 3, 129-131, 1999

Oral collision carcinoma: Salivary duct carcinoma of minor origin and squamous cell carcinoma of the oral mucosa

Yasunori Takeda and Hirotsugu Yamamoto•˜

Department of Oral Pathology, School of Dentistry, Iwate Medical University, Morioka, Iwate 020-8505 §Department of Pathology, Nihon University School of Dentistry at Matsudo, Matsudo, Chiba 271-8587

(Received 20 April and accepted 14 July 1999)

Abstract: This paper reports a case of oral collision The patient was examined and found to have a forefiger' carcinoma consisting of salivary duct carcinoma of minor tip-sized tumor (T2N0M0) in the floor of the mouth on the left. salivary gland origin and microinvasive squamous cell The tumor was mobile, but indurated on palpation. The carcinoma of the oral mucosa in a 65-year-old Japanese covering oral mucosa showed formation of a small ulcer, 7 mm man. This is an exceedingly rare example of collision in diameter, surrounded by a -like lesion. The carcinoma in the oral region. (J. Oral Sci. 41, 129-131, 1999) remainder of the physical examination revealed no unusual findings. After chemotherapy, the tumor was surgically Key words: collision carcinoma; oral region; salivary duct excised along a clinically normal margin, and a left radical neck carcinoma; squamous cell carcinoma. dissection was carried out. The patient remains alive, but a chest X-ray film suggests metastases in the left lung at the time of writing, 6 months later. Introduction The surgically excised specimen showed diffuse infiltration Multiple primary tumors may arise from different parts of of a salivary duct carcinoma with typical histologic features the same organ. Collision tumors, which can be benign or in the submucosal tissues and mucosa (Fig. 1), resulting in malignant, are synchronous, morphologically different formation of an ulcer of the covering oral mucosa. In addition, neighboring that expand into each other (1-3). To the oral mucosa around the ulcer showed a microinvasive the best our knowledge, few collision carcinomas in the oral squamous cell carcinoma, which was directly in contact with region have been reported (4). This paper describes an the parenchyma of the salivary duct carcinoma (Figs. 2, 3), exceedinglyrare example of oral collisioncarcinoma consisting and the border between the carcinomas was clear. of a salivary duct carcinoma of minor salivary gland origin and Immunohistochemical examination revealed clear cytological an early invasive squamous cell carcinoma of oral mucosa differences between the carcinomas: that is, the microinvasive origin. squamous cell carcinoma of the oral mucosa was distinctly positive for anti-human cytokeratin (high molecular weight, Case Report A 65-year-old Japanese male patient visited a local ENT- clinic in March 1998 because of a painless swelling on the floor of the mouth of 2 months duration. His father had died of carcinoma of the stomach, and his younger brother had died of carcinoma of the tongue. At that time, histopathologic examination of a fine-needle aspiration biopsy specimen showed the lesion to be a salivary duct carcinoma. The covering oral mucosa of the lesion showed a party leukoplakia- like appearance without ulceration, but it was not examined histopathologically. The patient was transferred to the dental hospital of Iwate Medical University for surgical treatment of the carcinoma in May.

Correspondence to Dr. Yasunori Takeda, Department of Oral

Pathology, School of Dentistry, Iwate Medical University, 19-1 Fig. 1 Infiltration of salivary duct carcinoma with typical Uchimaru, Morioka 020-8505, Japan histological features (HE; •~40). 130

between the carcinomas was clearly demonstrated by this immunohistochemical staining (Fig. 4).

Discussion Collision carcinomas have been considered to be the concrescence of two independently arising malignant neoplasms, so there should be separated neoplastic areas of two quite different histological patterns (1, 2). At an early stage in the evolution of collision carcinomas, the two components may be present as separate, dual, noncolliding carcinomas. It is reasonable to assume that in the course of growth of such neoplasms, the two components may invade each other (3). In some cases, even after attaining considerable size, the two components may remain intimately apposed, but do not invade Fig. 2 Microinvasive squamous cell carcinoma in the mucosa each other (3). around the ulcer formed by infiltration of salivary duct Collision carcinomas have been described in various locations, including the cervix, lung, anorectal junction, liver, urinary bladder, gastroesophageal junction, and others. However, review of the literature yields few cases involving collision of two carcinomas in the oral region (4). The lesion of the mouth floor in the present case showed diffuse infiltration of salivary duct carcinoma in the submucosal tissues and mucosa, resulting in formation of a small ulcer on the covering oral mucosa. In addition, the oral mucosa around the ulcer showed microinvasive squamous cell carcinoma, which was directly in contact with the parenchyma of the salivary duct carcinoma. Immunohistochemical examination using anti- human cytokeratin (high molecular weight) revealed a clear cytological difference between the two carcinomas. Such immunohistochemical results supported the conclusion that the lesion was a collision carcinoma. The diagnosis of salivary duct carcinoma in this case should Fig. 3 Collision of salivary duct carcinoma (left half) and be distinguished from basaloid squamous cell carcinoma, microinvasive squamous cell carcinoma (right half) (HE; which is a recently recognized variant of squamous cell ×20). carcinoma (5, 6). As well as its heterogeneous composition, the most important distinguishing pathologic feature of basaloid squamous cell carcinoma from other carcinomas is a focal squamous cell carcinoma component in the basaloid area (5, 6). In addition, the parenchymal cells of basaloid squamous cell carcinoma react with high-molecular-weight anti-human cytokeratin (7). In the present case, the parenchyma diagnosed as salivary duct carcinoma showed a homogeneous composition without any squamous cell carcinoma component, and was negative for anti-human cytokeratin of high molecular weight. Furthermore, the clinical finding at the onset of the symptoms was submucosal swelling of the mouth floor without ulceration in the covering oral mucosa. Pseudoepitheliomatous hyperplasia, or pseudocarcinomatous hyperplasia, as it is often called, represents a considerable Fig. 4 Anti-human cytokeratin (high molecular weight) proliferation of epidermis or mucous epithelium, and may immunohistostain of collision carcinoma, appearing positive occur in chronic proliferative inflammatory processes or at the in the microinvasive squamous cell carcinoma (right half) edges of chronic ulcers. Clinically and histologically, such and negative in the salivary duct carcinoma (left half). hyperplasia may occasionally suggest a squamous cell carcinoma. However, the histological feature present in DAKO, code No.M630), and the salivary duct carcinoma of squamous cell carcinoma, but absent in pseudoepitheliomatous minor salivary gland origin was negative (Fig. 4). The border hyperplasia, is marked cellular atypia (8). In the present case, 131 the oral mucosa around the ulcer clinically showed a References leukoplakia-like appearance and histologically showed 1. Meyer, R. (1919) Beitrag zur Verstandigung tiber die prominent cellular atypia of thickened mucous epithelium, Namengebung in der Geschwulstlehre. Zentralbl. Alle involving the most superficial region of the underlying Pathol. 30, 291-296 connective tissue, just beneath the basement membrane. Such 2. Dodge, O.G. (1961) Gastro-cesophageal carcinoma of a histopathological finding supports the diagnosis of mixed histological type. J. Pathol. Bact. 81, 459-471 microinvasive squamous cell carcinoma (6). 3. Spagnolo, D.V., and Heenan, P.J. (1980) Collision When two events coincide it is assumed that the relationship carcinoma at the esophagogastric junction: report of two is fortuitous, but it is also acknowledged that an association cases. Cancer 46, 2702-2708 of very unusual circumstances may suggest a causal relationship 4. Sirsat, M.V. and Shrikhande, S.S. (1966) Collision between them. Although a causative factor for collision tumor in the oral cavity (a report of 2 cases). Indian J. carcinoma was not apparent in the present case, three possible Pathol. Bacteriol. 9, 340-343 causes for the existence of collision neoplasms have been put 5. Barnes, L., Ferlito, A., Altavilla, G., MacMillan, C., forward (9). The first hypothesis to explain the coexistence Rinald, A. and Doglioni, C. (1996) Basaloid squamous of distinct carcinomas next to each other is that a carcinogen cell carcinoma of the head and neck: clinicopathological could theoretically interact with and cause neoplasms in two features and differential diagnosis. Ann. Otol. Rhinol. neighboring histologically distinct tissues. This is more likely Laryngol. 105, 75-82 to occur in patients with an inherited predisposition to develop 6. Pindborg, J.J., Reichart, P.A., Smith, C.J. and van der carcinoma. The second possibility is the phenomenon known Waal, I. (1997) Definitions and explanatory notes. In as horizontal recruitment, which has been used to describe a Histological typing of cancer and precancer of the oral mechanism whereby carcinomas composed of host cells are mucosa, 2nd ed., Springer, Berlin, 11-16 induced at the site of transplantation of a malignant . 7. Morice, W.G. and Ferreiro, J.A. (1998) Distinction of This situation is limited to the domain of experimental oncology, basaloid squamous cell carcinoma from adenoid cystic but it is possible that the same mechanism could operate in and small cell undifferentiated carcinoma by spontaneous carcinomas. The third situation conducive to the immunohistochemistry. Hum. Pathol. 29, 609-612 generation of a collision carcinoma is when a slow-growing 8. Wolber, R.A., Talerman, A., Wilkinson, E.J. and carcinoma creates the circumstances that directly or indirectly Clement, P.B. (1991) Vulvar granular cell tumor with favour the genesis of a second lesion at the site, or next to the pseudocarcinomatous hyperplasia. a comparative first neoplasm. analysis with well-differentiated squamous cell carcinoma. Int. J. Gynecol. Pathol. 10, 59-66 9. Costa J. (1993) Critical commentary to "Collision tumor of squamous cell carcinoma and leiomyoma in the esophagus". Pathol. Res. Pract. 189, 363