Warthin's tumor with necrotizing tuberculous granulomatous inflammation causing severe facial nerve adhesion in parotid gland: A case report and literature review

RATIONALE

Warthin's tumor is the second most common tumor arising from the parotid gland, but it rarely occurs concomitantly with tuberculous granulomatous inflammation with only 13 documented case reports in the English literature.

PATIENT CONCERNS

An 82-year-old woman had a left infraauricular mass for approximately 3 years that had significantly increased in size over the previous 1 month.

DIAGNOSES

A diagnosis of Warthin's tumor was made by ultrasonography (US)-guided core needle biopsy. Pathological examinations of the specimen obtained by total extirpation confirmed that the tumor was superimposed with tuberculous granuloma.

INTERVENTIONS

The core biopsy wound did not heal and there was formation of a skin fistula tract with persistent discharge. During the operation with en bloc resection of the necrotic parotid tumor, adhesion between the branches of the facial nerve was too tight to allow preservation.

OUTCOMES

A diagnosis of necrotic Warthin's tumor superimposed with tuberculous granuloma was made. Due to the high-clinical suspicion of tuberculosis (TB) due to Mycobacterium tuberculosis infection, anti-TB chemotherapy was given.

LESSONS

Poor wound healing from a core biopsy and formation of a skin fistulous tract with persistent discharge should raise concern regarding potential extrapulmonary tuberculous infection. Although very rare, tuberculous granuloma concomitant with Warthin's tumor should be considered in the differential diagnosis of a parotid mass lesion. Adhesion of branches of the facial nerve should be expected, and sacrifice of the nerve may be planned. This consideration can be explained to the patient in preoperative counseling and planning. Anti-TB chemotherapy should be given in cases with a definite pathological report associated with speculative clinical presentation.

Adenolymphoma of the Parotid Gland

In the period 1928–1968 in a series of 355 benign and malignant tumors of the parotid observed at the National Cancer Institute in Milan there were 36 cases of adenolymphoma. The clinical, morbid anatomy and histogenetic features of these cases are described. On the strength of the following findings: normal salivary tissue enclosed within an intraparotid lymph node, the association of a mixed tumor and an adenolymphoma in the same gland, the bilaterality of the tumor in 2 cases and the functional activity demonstrated with 131I, the salivary origin of adenolymphoma is argued. As to treatment, given the biological characteristics of the tumor, enucleation/resection would seem to be the operation of choice. For various reasons, however, including the difficulty of a precise preoperative diagnosis, total parotidectomy, sparing the 7th cranial nerves, is more often performed.

Back to the roots of Warthin's tumor of the parotid gland

The exact etiopathogenesis of the Warthin's tumor of the parotid gland is still unclear. Since the time of the first histological description of this lesion by Hildebrand and later Albrecht and Arzt many different partly confusing hypothesis about pathogenesis of Warthin's tumor were introduced. However, the review of published data about the pathogenesis of this lesion revealed that recent literature is in conformity with the supposed hypothesis about pathogenesis of Warthin's tumor of those authors about the origin of this lesion from lymph nodes almost a century ago.

Using time-dependent covariate analysis to elucidate the relation of smoking history to Warthin's tumor risk

The authors aimed to elucidate the relation of the time-dependent smoking history parameters--age at smoking initiation and smoking intensity, duration, and latency--to the risk of Warthin's tumor, a benign tumor of the salivary gland for which cigarette smoking is a strong risk factor. They studied 117 cases of Warthin's tumor and 336 matched controls included in an Israeli nationwide case-control study of parotid gland tumors conducted from 2002 to 2003 by using the Cox regression model with time-dependent covariates, with age as the time axis. When current age and smoking duration were included in the statistical model, the authors show that the coefficient of a latency variable does not represent latency as such, but a balancing of the effects of age at initiation and time since cessation. They found a strong positive linear effect of duration of smoking, together with a positive nonlinear effect of intensity that levels off at higher intensities, and a negative effect of latency from 25 years onward. The latter finding implies that the effect of time since cessation dominates the effect of age at initiation, with risk decreasing sharply after smoking cessation. The relation of smoking variables to Warthin's tumor agrees with the patterns reported for lung cancer.

High risk for bilateral Warthin tumor in heavy smokers--review of 185 cases

CONCLUSIONS

We identified smoking as a significant risk factor for multilocular Warthin tumor development. Therefore, we recommend taking history of smoking into account when making the decisions for surgical strategy.

OBJECTIVES

Warthin tumor is a common benign neoplasm of the parotid gland. Risk factors for multilocular development have not been defined.

PATIENTS AND METHODS

A total of 185 consecutive patients treated for Warthin tumor were included. Charts were reviewed for symptoms, risk factors, and diagnostic and surgical procedures. Patients were followed for facial function and recurrence. Risk factors were evaluated.

RESULTS

Overall, in 203 parotid operations, a lateral parotidectomy (77%) was performed in most cases; 94% were primary surgery and 6% were revision surgery. In 89% of patients swelling was the only symptom. Bilateral Warthin tumor was seen in 17% of patients. Of these cases synchronous and metachronous bilateral tumors were observed in 61% and 39%, respectively. The median time period for second contralateral tumor development was 7 years. Postoperative transient facial dysfunction was observed in 31%, which recovered within 3 months in all cases. Evaluation of risk factors revealed that 89% of the subjects were smokers and 66% were heavy smokers. The risk for bilateral Warthin tumors correlated significantly with the amount of nicotine intake (p=0.003).

Clinical features of cystadenolymphoma (Warthin’s tumor) of the parotid gland: A retrospective comparative study of 96 cases

The details of the etiopathogenesis of cystadenolymphoma (Warthin's tumor) are still unclear. To explore the possible risk factors for the development of this tumor, medical records of 81 patients with 96 Warthin's tumors of the parotid glands were compared retrospectively with those of 91 patients with pleomorphic adenoma. The medical history and clinical tumor characteristics of all patients were similar. There were no significant differences between these two patient groups with respect to concomitant diseases, regular medications, and preoperative laboratory findings. However, a significant male predominance of patients with Warthin's tumor could be noted (P<0.05). The male to female ratio was 3.3:1 in patients with Warthin's tumor. Multifocal Warthin's tumor were detected in five cases (6.2%), and 10 patients (12.3%) had bilateral lesions. The odds ratio for the incidence of Warthin's tumor among current smokers compared with never smokers was 8.3 (P<0.0001). Compared with never smokers, clearly higher odds of Warthin's tumor was observed in heavy smokers (more than 30 pack-years) (odds ratio=24.1, P<0.0001) than patients who smoked less than 30 pack-years (odds ratio=4.9, P<0.0001).

Warthin's tumor with multiple granulomas: A clinicopathologic study of six cases

Granulomatous inflammation occurring in Warthin's tumor is a rare phenomenon. It has been suggested that prior fine-needle aspiration (FNA) might be a triggering factor. We studied cases of Warthin's tumor with granulomatous inflammation to analyze the possible relationship with prior FNA. Granulomatous inflammation was noted in 6 cases (1.6%) of 382 cases of Warthin's tumor in a medical center. Clinical history, histology, and cytology slides were reviewed. Special stains for detection of infective agents were performed. All 6 cases showed typical features of Warthin's tumor accompanied by multiple granulomas. No specific microbiologic infective agents were revealed in these cases. There were 2 cases with history of preoperative FNA; both already had granulomas in Warthin's tumor in cytologic specimens taken by aspiration. The pathogenesis of granulomatous inflammation in Warthin's tumor remains speculative. Our observation of granulomas in the cytology specimens did not support the hypothesis of prior FNA being the cause.

Warthin's tumour and smoking

OBJECTIVE

In an evaluation of our patients with parotid gland neoplasms, we noticed that patients with a Warthin's tumour were heavy smokers. The aim of this study was to confirm earlier findings in the literature concerning a possible association between smoking and the development of a Warthin's tumour.

METHODS

A case control study was performed using the clinical records and discharge letters of all consecutive patients with a Warthin's tumour in the pathology database of our hospital covering the last 15 years. Patients with a pleomorphic adenoma and a group of patients visiting our audiology department were used as controls.

RESULTS

A smoking history was found in 97.5% of the patients with a Warthin's tumour. Of the patients with a pleomorphic adenoma, 59% had a smoking history; 56.5% of the audiology group had a smoking history. Mean age at the time of the operation was 60.1 years of age in the Warthin's tumour group and 48.6 for the pleomorphic adenoma group.

CONCLUSION

The mean age for the development of a Warthin's tumour is ten years older than for a pleomorphic adenoma. Furthermore, the development seems to be closely related to smoking habits.

Mitochondrial DNA mutations in the parotid gland of cigarette smokers and non-smokers

It has previously been demonstrated that mitochondrial DNA (mtDNA) mutations accumulate in the lung and increase in frequency with age. It has also been shown that the level of mtDNA mutations including deletions and base substitutions are elevated in lung tissue of smokers relative to non-smokers. We have previously shown that the 'common' 4977 bp mtDNA deletion is present in the parotid (salivary) gland of smokers and non-smokers and that there is a significant increase in the level of this deletion in Warthins tumour, an oncocytoma of the parotid gland. In this study we used semi-quantitative PCR to confirm the presence of 4977 bp mtDNA deletion in the parotid gland of non-smokers and smokers. Importantly, we show that the deletion accumulates with age regardless of smoking status and that there was no significant difference in the level of the 4977 bp deletion in parotid tissue of smokers and non-smokers. Using strand conformational polymorphism (SSCP) and direct sequencing we also found 5/23 smokers had parotid tissue specific base substitutions: either an A/T to G/C transition at A4767 or a G/C to A/T transition at G4853. These results are evidence of age related increase in the 4977 bp deletion and a higher level of mutations, probably due to oxidative damage, in the parotid gland of smokers.

Role of Epstein-Barr virus and cytomegalovirus in the etiology of benign parotid tumors

BACKGROUND

Pleomorphic adenomas and Warthin's tumors are the two most common benign parotid tumors. Previous studies investigating the role of viruses in tumorigenesis of these neoplasms have been conflicting. The aim of this study was to determine whether Epstein-Barr virus (EBV) or cytomegalovirus (CMV) might play a role in the pathogenesis of pleomorphic adenomas and Warthin's tumors.

METHODS

Paraffin-embedded surgical specimens of 24 pleomorphic adenomas, 10 Warthin's tumors, and 13 normal parotid tissues were obtained from the University of California-San Francisco Pathology Department. Genomic DNA was extracted from the specimens, and primers for connexin 26, a gap junction protein, were used to confirm the integrity of this DNA. The presence or absence of EBV and CMV DNA within the samples was determined with PCR-based assays, in which radiolabeled primers were used for maximal sensitivity of detection.

RESULTS

PCR analysis of serially diluted control DNA revealed that using radiolabeled primers, five copies of viral DNA could be detected. By use of this method, we showed that none of the 24 pleomorphic adenomas, 10 Warthin's tumors, or 13 normal parotid samples contained EBV DNA or CMV DNA.

CONCLUSIONS

These results do not support CMV or EBV as etiologic factors in pleomorphic adenomas or Warthin's tumors. In addition, normal parotid seems not to harbor either of these viruses. Future studies with larger numbers of specimens are needed to confirm these findings.

Metaplastic (infarcted) Warthin's tumour of the parotid gland: a possible consequence of fine needle aspiration biopsy

AIMS

The metaplastic (or infarcted) variant of Warthin's tumour is characterized by replacement of much of the original oncocytic epithelium by metaplastic squamous cells, along with areas of extensive necrosis, fibrosis and inflammatory change. The pathogenesis is unknown, but it is most likely to be vascular in origin. An association with a previous fine needle aspiration (FNA) has been suggested, and this is explored further.

METHODS AND RESULTS

Nine metaplastic Warthin's tumours were collected from several centres: all arose in the parotid gland, and all showed the characteristic histological features. Eight had previously undergone FNA some 1-4 months before surgery; the other case had had an incisional biopsy.

CONCLUSIONS

It is important to recognize metaplastic Warthin's tumour, because the differential diagnoses of this benign neoplasm include mucoepidermoid and squamous carcinoma, both primary and metastatic. The tumours in this study followed FNA or biopsy, and we believe this association is unlikely to be coincidental. Although many metaplastic Warthin's tumours clearly arise spontaneously, we conclude that the balance of probabilities favours the view that FNA is capable of causing metaplastic change in a Warthin's tumour, and may have done so in these cases. If so, this previously unusual subtype will become increasingly common, as FNA becomes more widely used (and its value appreciated) in the investigation of patients with a mass in the neck.

Smoking and the development of Warthin's tumour of the parotid gland

The smoking history was surveyed in 160 consecutive patients with Warthin's tumour of the parotid gland in order to investigate the relationship between smoking and the development of this tumour. Two hundred cases of middle-aged or elderly normal persons and 163 consecutive patients with pleomorphic adenoma in the parotid gland served as controls. The percentage of smoking in patients with Warthin's tumour (96.3%) was much higher than that of middle-aged or elderly normal persons (25.5%) and in patients with pleomorphic adenoma (26.4%). Moreover, the amount of smoking was greater and the smoking history was longer in patients with Warthin's tumour. When the male and female patients were analysed respectively, the same result was shown. This case-control study suggests that smoking may be one of the aetiologic factors associated with the development of Warthin's tumour.

Malignant oncocytoma of major salivary glands. Report of a post-irradiation case

The fourth case of malignant oncocytoma arising in the submandibular gland is here reported. This tumor arose in a 48-year-old man after radiation exposure, a finding never described before for malignant oncocytoma. In addition, several regional metastatic lymph nodes were found. The diagnosis was confirmed by histochemical and ultrastructural findings. The tumor cells showed easily recognizable mucus production and, ultrastructurally, abundant mitochondria, intracytoplasmic lumina lined by microvilli and lipid droplets. These last features have only seldom been described in malignant oncocytoma. Furthermore, the neoplastic cells were alpha-1-antitrypsin positive and S100, thyroglobulin, carcinoembryonic antigen, and smooth muscle actin negative. A thorough review of the literature is also presented.

Warthin's tumor and cigarette smoking

Warthin's tumor is a relatively uncommon salivary gland neoplasm, traditionally considered a disease of men. Recent reports have brought this assumption into question by identifying a substantial percentage of patients who are women. Furthermore, several reports have attempted to correlate cigarette smoking with development of Warthin's tumor. We retrospectively studied all cases of parotid tumor entered in the Brooke Army Medical Center Tumor Registry from 1973 to 1993. Relative percentages of benign and malignant disease, as well as frequency of individual tumor types, in general mirrored those in earlier reports. A high proportion of Warthin's tumor-23% of all tumors-was identified. More than one third of patients with Warthin's tumor were women. Also, 94% of patients with Warthin's tumor had a history of tobacco use; for all other tumor types combined, only 60% of patients had a history of tobacco use. This statistical difference supports the correlation between cigarette smoking and Warthin's tumor.

[Warthin tumor of the palate: an unusual location]

Warthin's tumor (papillary cystadenoma lymphomatosum) primarily involves the parotid gland, whereas localization in the palate has been reported by a few authors. A new case of true Warthin's tumor arising from the hard palate is here presented and histogenesis and differential diagnosis are briefly discussed.

CASE REPORT

A 50 year-old woman who was referred to us because of the presence of multiple contiguous bluish cyst-like lesions involving both sides of the hard palate mucosa. The lesion was removed with a wide excision involving almost all the soft tissues of the hard palate. Histologic diagnosis (E.E stain) was: papillary cystadenoma lymphomatosum.

DISCUSSION AND CONCLUSION

The histogenesis of Warthin's tumor is still controversial. The most widely accepted theory is that the tumor represents a neoplastic proliferation of salivary gland ducts entrapped in pre-existing lymph nodes. In fact, immunohistochemical analysis and cell-surface markers studies have shown that the lymphoid component is predominantly formed by T-lymphocytes, with a relatively small number of polyclonal B-lymphocytes. On the contrary, other authors found opposite relationship between T and B lymphocytes. These findings supported the concept that lymphoid tissue in Warthin's tumor represented a reactive cellular infiltrate in a pattern similar to that seen in reactive lymph nodes. Similar results have been found in this report; moreover, the hard palate does not usually contain lymphatic tissue. This could support the idea that the lymphoid tissue associated with this case is reactive and a direct origin from the ductal epithelium with secondary lymphocytic infiltration is more likely to occur in this area.

Cigarette smoking and Warthin's tumor

The etiology of Warthin's tumor, a benign parotid gland tumor, is unknown. Recent evidence suggests a possible relation with cigarette smoking as well as increasing incidence. We reviewed the medical record of subjects with a major salivary gland tumor newly diagnosed in Jefferson County, Alabama, from 1968 to 1989, and identified 149 Warthin's tumors. The 533 cases with other major salivary gland tumors were used as controls. The analysis showed that 96% of Warthin's tumors occurred in whites. The relative incidence of Warthin's tumor among smokers versus nonsmokers was 7.6 for men (95 percent confidence interval 3.2-18.3; p < 0.001) and 17.4 for women (95 percent confidence interval 6.5-54.7; p < 0.001). Smokers of both sexes with Warthin's tumor smoked more heavily than did those with other salivary gland tumors (p < 0.001). From 1968 through 1988, Warthin's tumors steadily increased in number and as a proportion of salivary gland tumors (males, p = 0.003; females, p = 0.008). We also observed a significant increase in the incidence rate for Warthin's tumor (p = 0.041) but not for other salivary gland tumors. We conclude that Warthin's tumor is strongly associated with cigarette smoking and that the incidence rate is increasing. The disease is rare in blacks.

[Warthin's tumor. Description of 2 cases]

Warthin's tumor is a debated pathological condition. There are many controversies concerning this disease such as its origin (hereditary or acquired), its nature (whether neoplastic or no), its topographical relation with the salivary glands, its relationship with possible concomitant pathologies (dysmetabolic, infective, neoplastic, etc.), the problems of diagnosis and of differential diagnosis with all possible causes of cervical swelling, and also the problems of surgical treatment in relation to the possible involvement of the salivary glands. In this paper two clinical cases are described. The first one is characterized by a latero-cervical bilateral Warthin's tumor, apparently independent of the salivary glands, associated with rhinopharyngeal lymphatic hyperplasia and nodular colloid goiter. The second case is characterized by a latero-cervical uni-lateral Warthin's tumor, linked by a slender layer with the ipsilateral parotid gland, associated with breast cancer. Starting point from the discussion of these two cases, the Authors make remarks in order to answer some of the aforementioned questions.

[Smoking and the development of Warthin tumor of the parotid gland]

The smoking history was surveyed in 128 cases with Warthin tumor of parotid gland in order to investigate the relationship between smoking and the development of the tumor. Two hundred cases of middle or old age normal persons and 136 cases with pleomorphic adenoma in parotid gland served as the controls. The percentage of smoker in patients with Warthin tumor (96.9%) was much higher than that of middle or old age normal persons (25.5%) and patients with pleomorphic adenoma (24.3%). Morever, the amount of smoking was greater and the smoking history was longer in patients with Warthin tumor. When the male and female patients were analysed respectively, the same results were shown. This case--control study suggests that smoking may be one of the etiologic factors associated with the development of Warthin tumor.

Warthin's tumor: a 40-year experience at The Johns Hopkins Hospital

Warthin's tumor previously has been thought to occur much more commonly in men than in women and rarely in African Americans. One hundred thirty-two cases of Warthin's tumor treated at The Johns Hopkins Hospital from 1952 to 1992 were retrospectively reviewed. There were 90 (68%) men and 42 (32%) women, with an overall man-to-woman ratio of 2.2:1. The number and percentage of women with Warthin's tumor increased over each consecutive decade: 1952 to 1962, 5 (21%); 1963 to 1972, 6 (29%); 1973 to 1982, 11 (31%); and 1983 to 1992, 20 (39%). A positive smoking history was found in 88% of the men and in 89% of the women with a Warthin's tumor. Eleven (8%) African Americans and 1 (0.75%) Asian American were diagnosed to have a Warthin's tumor. Also, the incidence of African Americans with a Warthin's tumor increased over each decade: 0 (0%), 1 (4.8%), 2 (5.5%), and 8 (16%). This study's results indicate a progressive increase in the occurrence of this tumor in women and in African Americans and a higher overall incidence in African Americans than previously reported.

Smoking as an etiologic factor in the development of Warthin's tumor of the parotid gland

In order to further examine a preliminary association between smoking and the subsequent development of Warthin's tumor, a case-control study was undertaken between the years 1980 and 1989. Consecutive patients with Warthin's tumor served as cases, and consecutive patients with pleomorphic adenomas served as controls. A positive history of smoking was defined as a patient with greater than a 10-pack year history. There were 28 cases and 69 controls (ratio: 1:2.5). The number of male to female patients with Warthin's tumor and pleomorphic adenoma was 22 to 6 (3.7:1) and 22 to 47 (1:2.1), respectively. The mean age at presentation with Warthin's tumor or pleomorphic adenoma was 60.7 years and 40.7 years, respectively. In those patients for whom a definite smoking history was known (93 patients), an odds ratio of 8.1 (p < 0.001) was calculated. In order to exclude sex as a possible confounder, the odds ratio in males only was 6.4 (p = 0.007). In order to exclude age as a possible confounder, the odds ratio in all patients over 45 years (48 patients) was 11.2 (p < 0.001). In summary, smokers have eight times the risk of developing a Warthin's tumor than nonsmokers. This case-control study suggests that smoking may be one of the etiologic factors associated with this benign salivary gland tumor.

Smoking predisposes to parotid adenolymphoma

Of 574 patients with previously untreated, unremarkable parotid lumps, 194 proved to have pleomorphic adenomas and 73 adenolymphomas. ABO blood group details were available in 59 and 85 per cent of patients respectively. Smoking details were available in 84 per cent of a randomly chosen 46 per cent subgroup of patients with pleomorphic adenomas and in 86 per cent of all those with adenolymphomas. The incidences of smoking and of the ABO blood groups in these two diagnoses were compared with standard sources. There was no evidence that either histological diagnosis of parotid tumours was linked to an abnormal pattern of ABO blood groups. However, there was a much greater incidence of smoking among the adenolymphoma than in the pleomorphic adenoma group: only one of 63 patients with adenolymphoma as opposed to 31 of 75 with pleomorphic adenoma had never smoked, while the mean number of cigarettes smoked by each patient with an adenolymphoma was estimated to be 300,000 as opposed to 80,000 for those with pleomorphic adenoma.

Warthin's tumor: multicentricity and increasing incidence in women

Warthin's tumors comprised 14 percent of all parotid tumors operated on. The average patient age in our series was 57.2 years. Eighty-seven percent of the tumors occurred in the parotid tail. The rest were in the deep lobe, or in an extraparotid location. Fifteen patients had multifocal tumors. The maximum number of tumor foci in one patient was six. A significant increase in the female incidence was noted with a 1.5:1 male-to-female ratio as compared with the previous male dominant ratio of 8:1. Eighty-two percent of the female patients in our group were smokers. We correlated a very high incidence of cigarette smoking in our series when compared with age-matched groups in both sexes within the general population. Since it is estimated that one of eight patients with Warthin's tumor will have multifocal disease, we suggest wider exposure and more meticulous operative exploration to avoid overlooked synchronous tumor foci and subsequent recurrence.

Adenolymphoma of the parotid: aetiology, diagnosis and treatment

In order to study the changing clinical pattern, diagnosis and surgical treatment of adenolymphoma, the records of all 57 patients with a confirmed histological diagnosis, made at Bristol Royal Infirmary between 1951 and 1984, were reviewed; in 3 patients (5 per cent) bilateral lesions had been found. No characteristics emerged in a review of the history and clinical examination which would have enabled a correct preoperative diagnosis to be made. During the period of study the incidence of adenolymphoma increased 24-fold. (Parotid pleomorphic salivary adenomas increased in incidence by only 42 per cent over the same period). Before 1965 all patients were men; between 1965 and 1975 the male to female ratio was 3:1; between 1975 and 1985, 1.6:1. Of the 48 patients who had a relevant history taken 45 were smokers (93.8 per cent). It is postulated that tobacco consumption is important in the development of adenolymphoma, and has produced the changes in incidence and sex ratio. Fine needle aspiration biopsy cytology (FNAB) afforded the only method of achieving a pre-operative diagnosis. This was successful in 64.7 per cent. Superficial parotidectomy induced a 43 per cent incidence of facial nerve neurapraxia. Controlled enucleation reduced this to 8 per cent. Enucleation is the procedure of choice for adenolymphoma but can only be employed with confidence if an exact pre-operative diagnosis is made.

Radiation-induced parotid cancer

A retrospective analysis of 72 cases of primary malignant tumors of the parotid gland treated at the University of Illinois Hospital, Chicago, from 1950 through 1978 revealed that six of these had developed from two to 24 years after irradiation of the head or neck for various benign and malignant neoplastic conditions. At the time of irradiation, ages ranged from 7 to 73 years; the sex distribution was equal. From our findings and those in 26 cases reported by various other authors, the following criteria are proposed for the designation of a parotid tumor as being radiation induced: (1) well-documented radiation exposure; (20 port of irradiation must incorporate the gland in which the cancer subsequently arises; (3) exposure to a minimum of 300 rads; and (4) minimum latent period of two years. In view of the widespread use in the past of head and neck irradiation of benign neoplastic disease, the surgeon should be aware of this possible link with parotid gland tumor.

Warthin's tumor: an immunohistochemical study of its lymphoid stroma

The lymphoid stroma of Warthin's tumor was studied using an immunoperoxidase method. We found that IgA plasma cells constituted approximately 80 per cent of the total number of plasma cells in this tumor. IgA was present also in the tumor epithelium and in the intraluminal sections. The predominance of IgA plasma cells in Warthin's tumor is in contrast to the lymphoid pattern observed in autoimmune diseases and usual host-tumor reactions. It seems likely that the lymphoid stroma of Warthin's tumor represents an exaggerated secretory immune response. The neoplastic tissue of Warthin's tumor may elaborate or contain an unknown factor that causes the accumulation of lymphoid tissue and the differentiation of IgA plasma cells.