Metastatic adenocarcinoma of the jaws of unknown origins

 H. A. El-Abdin, BDS, FDSRCS
College of Dentistry, King Saud University, P.O.Box:60169, Riyadh 11545, Saudi Arabia

 
 Metastatic malignant tumors from distant primary focci to the bones and soft tissues of the jaws and the oral cavity are very rare with only few cases reported yearly. The diagnosis of these tumors is not a problem,however, the location of the primary focci may be the real problem. In most cases, oral metastasis is the first sign of a malignant tumor. This usually indicates a widespread lesion of poor prognosis and high mortality rate. The purpose of this article is to draw the attention of oral and maxillofacial surgeon to this unusual tumor category of the oral cavity, and to emphasize the complementary relation between oral surgery and other branches of the medical profession.

 
A challenging clinical problem is that of a patient presenting with an evidence of metastatic disease but no apparent primary site.Metastatic tumors of the jaws and oral cavity are rare, which represent about 1% of all oral malignan­ cies.1 In most cases, the metastatic lesions are detected in patients with known malignancies. How­ ever, in 20-30% the recognition of the jaw lesion may be the first evidence of dissemination of the unknown primary tumor.2,3,4 Such a situation is reported to occur in as much as 61 % of all the cases.5 Of these cases, 10 to 15% ended up with an un­ known primary site. When such problem arises, there could be a difficulty deciding on the investigative procedures to identify the primary site of the tumor.6
In this study, we report two cases of metastatic adenocarcinoma of unknown origin in the mandi­ ble, the maxilla, and the soft tissues of the oral cav­ ity, with different clinical pictures but identical problem in finding the primary tumors.
Case One:
A 65-year-old female patient was referred from the medical department of King Khalid University Hospital when she has been admitted one month previously, with an acute pulmonary embolism and recurrent attacks of thrombophlebitis in her right leg.
The patient was complaining of a painful swel­ ling in her lower right jaw, with anesthesia and paraesthesia of the lip [Fig. 1]. For one year, the swelling was firm and tender. The lower right first premolar was extracted on the assumption that the condition was an odontogenic infection, for which she was placed on a long course of antibiotic treat­ ment. This was followed six months after the lower right molar has been extracted, on the same assumption, to effect drainage. A little improve­ ment was noted by the patient. The swelling was confined to the premolar-molar area, and the over­ lying skin and the mucosa was normal with no evi­ dence of inflammation.
Conventional radiographs showed areas of radiopacity with areas of radiolucency [Fig. 2]. CT-
scan of the mandible revealed the mass to be sub­ periosteal, surrounding both the buccal and lingual cortex [Fig. 3]. Histological examination of the specimens showed lamellar bone trabeculae being destroyed and replaced by neoplastic epithelial cells in acinous formations. Mitotic figures were evident as well as tumor giant cells [Fig. 4a].
An immunohistochemical stain with peroxidase-ahti-peroxidase for epithelial antigen (EMA) and mucin stain (PAS) proved positive, and the lesion was diagnosed as an adeno- carcinoma of the metastatic type [Fig. 4b].
An exhaustive search for the primary tumor was conducted with a mammography, repeated total body scanning, and ultrasonography of the breast, kidney, liver, ovaries, and pancreas. This proved negative since no primary tumor was found. A magnetic resonance imaging was arranged at the Riyadh Military Hospital but the patient died before it could be done.
Case Two:
A 45-year-old male patient was referred to our Clinic with a one month-old swelling of his right maxilla, and bilateral white exophytic growth in his retromolar areas [Fig. 5]. The patient had been hos­ pitalized with a history of low grade fever and loss of weight. He had been diagnosed as a case of Malta fever and had been treated accordingly with no improvement. The oral swelling was painless and involved the alveolar mucosa opposite the premolar teeth. The patient looked pale, cachectic, and seve­ rely ill [Fig. 6]. His radiographs were all negative.
Consultations were made with a nephrologist, a gastroenterologist, and a radiologist. Intravenous pyelogram, ultrasonography, endoscopy, and skeletal survey were all performed on the patient under local anesthesia and the findings were nega­ tive, except for the skull radiographs which showed evidence of brain metastases. The latter appeared to explain the unremitting fever.
In view of the brain metastases, the prognosis was regarded as hopeless. The patient died two weeks later.

The management of patients with metastatic tumors of unknown origins presents a most formid­ able problem in clinical oncology.7 Accurate diag­ nosis of such tumors is essential because some of them are potentially curable and many are amena­ ble to effective palliative chemotherapy or radiotherapy.8 Clinical research has led to con­ stantly improving methods of cancer treatment and no clinician would doubt the importance of know- ing the precise type and site of the malignant tumor before treatment planning and therapy. Merely establishing the type of the metastatic tumor is not sufficient since the specific site in a specific organ may necessitate some specific local or systemic therapy.

Localization of the primary tumor is often dif­ ficult and sometimes impossible.9,10,11 In a study on 162 patients, with metastatic adenocarcinoma of undetermined origin at the Mayo Clinic, the pri­ mary sites could be established with reasonable certainty in only 42 cases. The study involved care­ ful autopsy examination, whenever permitted, and showed carcinoma of the pancreas, body or tail, gastro-intestinal growth, kidney, breast, and pros­ tate as the major sources of the primary tumor.12
In the oral cavity, metastatic tumors either involve the soft tissues, like gingivae and tongue, or the jaw bones, commonly the mandible, where they appear as an osteolytic lesions on radiog­ raphs. Very rarely, they may show as an osteoblas­ tic lesion with evident bone deposition. Many metastatic lesions were erroneously diagnosed as benign tumors, commonly ameloblastomas or cysts, and sometimes osteomyelitis and granulomas of either bone or soft tissues. Only his- topathology reports could confirm the metastatic nature of the tumors. For some tumors where the primary sites were not evident or could not be found, they were considered as primary growths and the central growths were explained as ectopic salivary gland tissue trapped in bone during early embryonal development of the mandible.
Surgery in the treatment of metastatic tumors of the oral cavity is rarely indicated. Symptomatic or palliative treatment, such as radiotherapy and/or chemotherapy, may be used. Chemotherapy for adenocarcinoma of unknown origin has been reported, but the results were unfavorable.12 The goal of the treatment is to retard the progress of the lesion, relieve pain and prevent infection, pathologic fracture, hemorrhage, and cachexia.
In our patients, one suffered from an unexplained recurrent attack of thrombophlebitis and the other from fever of unknown origin, which was clinically managed as Malta fever. Both cases proved to be metastatic malignancies to the oral cavity.

The author would like to express his sincere thanks and gratitude to Prof. Axel Ruprecht for his valuable and treasured advise as well as reading the manuscript. My thanks are also extended to Ms. Millet A. Rendon of the Research Center for her secretarial assistance and to Mr. Roily Abanto of the Audio-Visual Department.