ARTICLE
Benign cystadenoma [1] and certain malignant carcinoma (especially the
well-differentiated cystic mucoepidermoid carcinoma and the papillary
cystic type of acinic cell carcinoma) [1] of the minor salivary glands
clinically resemble salivary gland cysts. However, in contrast to the
latter, the former, although representing crucial differential diagnoses,
are not well recognised in the dermatological literature. Furthermore,
a rare secondary occurrence of real salivary gland neoplasms in preexisting
salivary gland cysts has been reported [2].
Case report
A 39 year old female presented with an asymptomatic bluish tumor on
the buccal mucosa which had grown slowly for one and a half years. A similar
appearing lesion at the same location had been excised, 14 years previously.
Its histological evaluation had confirmed a mucous retention cyst.
Physical examination revealed a 1.5 x 1 cm elastic,
non-adherent multicystic bluish tumor on the buccal mucosa next to the
first molar (Fig. 1).
Lymphnodes and laboratory findings were unremarkable.
Total excision of the lesion was achieved. Histological examination
revealed a multicystic tumor limited by a condensed lamina propria beneath
the epithelium of the oral mucosa. The lining epithelium of the cystic
lumen consisted in some areas of a bilayered, in others of a multilayered
salivary duct epithelium with papillary projections into the cystic spaces,
which contained secretory material. Epithelial cells with PAS-positive
cytoplasmatic granules reminded us, to an extent, of apocrine secretion.
Cellular atypia and mitoses were absent. A papillary cystadenoma was diagnosed.
Unfortunately, the histological specimens from the first excision performed
elsewhere were no longer available for reevaluation. The patient is being
followed closely. No recurrence has occurred, so far.
Discussion
Salivary gland cysts are often observed in the oral cavity. They result
from the presence of a circumscribed collection of mucus within the submucosal
tissues. In most cases, an epithelium is absent and the mucin is directely
enclosed by a wall of compressed and chronically inflamed connective tissue
(extravasation type). Some mucous cysts (retention type) are true cysts
and show a mucin-filled cavity surrounded by a thin distended layer of
epithelium and a connective tissue wall [2, 3]. Less common, real epithelial
neoplasms occur in the minor salivary glands [4-9]. The broad variety
of benign and malignant tumor entities has been histologically classified
by the WHO in 1972 [10] and revised in 1992 [1, 11, 12] (Table
I). The clinical differential diagnosis of salivary gland cysts
primarily has to take into account benign cystadenomas, the malignant
well-differentiated cystic mucoepidermoid carcinoma [2] and the papillary
cystic type of acinic cell carcinoma [1]. In our case, the histology was
characteristic for a papillary cystadenoma. Histologically, it closely
resembles the so-called Warthin tumor with absence of the lymphoid elements.
The apical PAS-positive cytoplasmatic granules in our case recalled apocrine
metaplasia providing evidence of a biological relationship between minor
salivary glands and cutaneous apocrine glands. A phylogenetical context
of these tissues has earlier been suggested by the expression of GCDF-15
(gross cystic disease fluid), they have in common [13, 14].
Most cases of papillary cystadenoma have occurred
in the larynx. Manifestation in the major and minor salivary glands are
rare [1]. The papillary cystadenoma mostly occurs between 6-9th decade
without sex predominance [15]. In contrast, the similarly appearing benign
mucinous cystadenoma is lined by mucous-producing cells or goblet cells.
The differentiation of this tumor from its more common malignant counterpart,
however, is difficult and is based on the tumor's circumscription and
absence of cellular atypia [1, 2]. The mucoepidermoid carcinoma consists
of mucous forming cells, epidermoid cells and sometimes of intermediate
cells. In the well-differentiated type, however, there's no nuclear pleomorphism,
mitoses are absent or extremely rare [1]. Some forms of acinic cell carcinoma
may also present like our case. In general, the acinic cell carcinoma
consists of four different cell types: large acinic cells, vacuolated
cells, clear cells and non-specific glandular cells [1]. However, in the
papillary cystic type of acinic cell carcinoma a configuration with papillae
in cystic spaces is present [1] which may resemble papillary cystadenoma.
Thus, salivary gland histology is extremely hard to interpret and requires
special histological expertise [15].
Sporadic case reports mention the development of salivary gland tumors
(e.g. mucoepidermoid carcinoma and basal cell adenoma) in preexisting
salivary gland cysts [2]. It remains unclear, if, according to a long-standing
hypothesis, our case represents an example of secondary tumor development
in preexisting salivary gland cysts. In our case, 14 years prior to the
excision of the papillary cystadenoma, at the same location a mucous retention
cyst had been excised and histologically confirmed. These two tumors may
have occurred independently or instead, the papillary cystadenoma may
have developped in residuals of the mucous retention cyst. Recently, a
study of 1,661 salivary gland cysts revealed epithelial metaplasia and
proliferative activity in 3-10% of mucous retention cysts of the minor
salivary glands and salivary duct cysts of the parotid gland [2]. Plump
or papillary projections into the cystic spaces was regarded as possible
early manifestation of true tumor growth [2]. Our case with manifest papillary
cystadenoma and a past medical history of mucous retention cyst at the
same location may support this suggestion.
Since fine needle aspiration is not unequivocal in cystic tumors [16,
17] and the prognosis of specific types of salivary gland tumors depends
on their malignancy and adequate treatment measures [13, 18, 19], an early
excision of all cystic tumors resembling mucous retention cysts is mandatory,
since true adenomatous or carcinomatous tumor formation cannot be excluded
clinically.
CONCLUSION
Acknowledgement
We thank Professor Gerhard Seifert, Institute of Pathology, University
of Hamburg, Germany for histological co-evaluation.
REFERENCES
1. Seifert G, Brocheriou C, Cardesa A, Eveson JW. WHO international histologic
classification of tumours. Tentative histological classification of salivary
gland tumours. Pathol Res Pract 1990; 186: 555-81.
2. Seifert G. Mucoepidermoid carcinoma in a salivary duct cyst of the
parotid gland. Contribution to the development of tumours in salivary
gland cysts. Path Res Pract 1996; 192: 1211-7.
3. Spouge JD. Diseases of the salivary glands. In: Oral Pathology.
Mosby, Saint Louis, 1973; 431-3.
4. Beckhardt RN, Weber RS, Zane R, Garden AS, Wolf P, Carrillo R, Luna
MA. Minor salivary gland tumors of the palate: clinical and pathologic
correlates of outcome. Laryngoscope 1995; 105: 1155-60.
5. Chau MN, Radden BG. Intra-oral salivary gland neoplasms: a retrospective
study of 98 cases. J Oral Pathol 1986: 339-42.
6. Chou C, Zhu G, Luo M , Xue G. Carcinoma of the minor salivary glands:
results of surgery and combined therapy. J Oral Maxillofac Surg
1996; 54: 448-53.
7. Eveson JW, Cawson RA. Tumours of the minor (oropharyngeal) salivary
glands: a demogaphic study of 336 cases. J Oral Pathol 1985; 14:
500-9.
8. Isacsson G, Shear M. Intraoral salivary gland tumors: a retrospective
study of 201 cases. J Oral Pathol 1983: 12: 57-62.
9. Loyola AM, de Araujo VC, de Sousa SO, de Araujo NS. Minor salivary
gland tumours. A retrospective study of 164 cases in Brazilian population.
Eur J Cancer B Oral Oncol 1995; 31B: 197-201.
10. Thackray AC, Sobin LH. Histological typing of salivary gland tumours.
WHO international classification of tumours. World Health Organization,
Genova, 1972.
11. Seifert G, Sobin LH. WHO histological classification of salivary
gland tumours. A complementary on the second edition. Cancer 1992;
70: 79-85.
12. Seifert G. Histologic typing of salivary gland tumours. 2nd
edn., Springer, 1991.
13. Mazoujian G, Pinkus GS, Davis S, Haagensen DE Jr. Immunohistochemistry
of a gross cystic disease fluid protein (GCDFP-15) of the breast. A marker
of apocrine epithelium and breast carcinomas with apocrine features. Am
J Pathol 1983; 110: 105-112.
14. Swanson PE, Pettinato G, Lillemoe TJ, Wick MR. Gross cystic disease
fluid protein-15 in salivary gland tumors. Arch Pathol Lab Med
1991; 115: 158-63.
15. Seifert G. Speicheldrüsentumoren. In: Doerr W, Seifert G, eds.
Spezielle pathologische Anatomie. 2nd edn,Vol. 1/I. Berlin, Heidelberg,
New York: Springer, 1996; 301-781.
16. Cohen MB, Liung BM, Boles R. Salivary gland tumors.Fine-needle aspiration
vs frozen section diagnosis. Arch Otolaryngol Head Neck Surg 1986;
112: 867-9.
17. Orell SR, Nette WJ. Fine needle aspiration of salivary gland tumours.
Problems and pitfalls. Pathology 1988: 20: 332-7.
18. Chilla R, Casjens R, Eysholdt U, Droese M. Maligne Speicheldrüsentumoren.
Der Einfluþ von Histologie und Lokalisation auf die Prognose. HNO
1983; 31: 286-90.
19. Hickman RE, Cawson RA, Duffy SW. The prognosis of specific types
of salivary gland tumors. Cancer 1984; 54: 1620-4.
|
Version imprimable
