Salivary duct carcinoma of the larynx: report of a rare case.

Abstract

Salivary duct carcinomas are primarily high-grade, aggressive malignancies that affect men in the fifth and sixth decades of life. These tumors are usually found in the major salivary glands; rarely do they originate in the minor salivary glands. The distinctive feature of these neoplasms is their remarkable histologic resemblance to infiltrating ductal carcinomas of the mammary gland; both types of tumor feature epithelial and myoepithelial cells arrayed in solid, papillary, and cribriform patterns. To the best of our knowledge, only one case of a primary salivary duct carcinoma of the larynx has been previously reported. In this article, we describe a new case, and we review the literature on salivary duct carcinomas.

Introduction

Nonsquamous cell malignancies of the larynx account for less than 1% of all epithelial malignancies. (1-7) These neoplasms can be classified (albeit imperfectly) as being of eithersurface or subsurface origin (i.e., from seromucous glands). Most of these tumors belong to the latter subgroup; adenoid cystic carcinoma is the most representative of these tumors. All other salivary-type carcinomas are rare. Even pleomorphic adenomas are almost curiosities in the larynx. (7)

In this article, we describe a very rare case of a primary salivary duct carcinoma that arose in the larynx. Its histologic features resembled those of a ductal carcinoma of the breast (comedo type). To the best of our knowledge, only one other case of a primary salivary duct carcinoma in the larynx has been previously cited in the world literature. (8)

Case report

A 56-year-old man of good build underwent an emergency tracheostomy for stridor at our hospital. His recent medical history had included progressive hoarseness, occasional dyspnea of 2 months' duration, and a 1-month history of noisy breathing. He did not smoke cigarettes or drink alcohol excessively, but he did chew tobacco. Following the tracheostomy, findings on general and systemic examinations were within normal limits. However, examination of the larynx revealed the presence of a smooth mass in the right side of the larynx. The epiglottis and left hemilarynx were normal. The size and location of the mass prevented direct visualization of the right vocal fold and pyriform fossa. Endoscopy revealed that the mass was fixed to the right vocal fold and trachea; the esophagus and bronchial tree were uninvolved. No node was palpable in the neck. Findings on routine laboratory investigations and chest radiography were unremarkable.

The patient was taken to the operating room for a total laryngectomy with level 2,3, and 4 bilateral clearance and primary closure of the pharynx and the tracheostomy. The excised laryngeal specimen was a 4 x 3-cm lobulated growth. Its surface was grayish-tan and finely lobulated. Multiple sections were taken for paraffin embedding and routine histopathology. A single lymph node was also removed. It measured 2 x 1 cm, and its surface was grayish-white. The entire node was sectioned for histopathologic examination.

Microscopic analysis revealed that the tumor was made up of dilated ductal structures that were lined with a multilayered solid pattern of malignant epithelial cells. These cells were separated by fibrous septa, some of which had been infiltrated by lymphocytes. The cells exhibited prominent anisocytosis as well as anisonucleosis displayed in solid, papillary, and cribriform patterns. A fair number of mitotic figures was seen. The ductal structures featured well-defined areas of central necrosis that resembled comedocarcinoma of the breast (figure). Analysis of the lymph node sections revealed the presence of metastasis, as the morphology of these cells was similar to that of the cells in the primary tumor. Immuno staining was negative for estrogen and progesterone receptors and positive for epithelial membrane antigen. At the 1-year follow-up, the patient was healthy and symptom-free.

Discussion

Salivary duct carcinomas are primarily high-grade, aggressive malignancies that affect men in the fifth or sixth decade of life. These tumors are usually found in the major salivary glands; rarely do they arise from the minor salivary glands. (8,9) Descriptions of their clinical behavior have ranged from slowly developing to extremely malignant and rapidly fatal (with hematogenous and lymphatic dissemination.) (10-12)

To our knowledge, the only previously published case of laryngeal salivary duct carcinoma was reported in 1981 by Ferlito et al, who diagnosed the disease in a 54-year-old man with dysphagia and dysphonia. (8) Kleinsasser et al (9) and Hubner et al (13) initially classified an unusual group of salivary gland carcinomas under the term Speichelgangcarcinome. This group of carcinomas was later termed salivary duct carcinoma in the English-language literature by Fayemi and Toker in 1974. (14) Another term, carcinome canaliculaire, was coined by Leroux-Robert and De Brux in 1976. (15)

The distinctive feature of salivary duct carcinomas is their remarkable histologic resemblance to infiltrating ductal carcinomas of the mammary gland; both neoplasms feature epithelial and myoepithelial cells arrayed in solid, papillary, and cribriform patterns. The cellular structure of some salivary duct carcinomas also resembles that of prostatic adenocarcinomas. (14)

Adenocarcinomas of the larynx follow the anatomic distribution of the subepithelial glands and intraepithelial mucous glands of the larynx. The tumor in our patient arose from the surface, perhaps from the intraepithelial mucus-secreting glands of the larynx. Batsakis et al published an excellent review of the number, distribution, and density of the glands in the normal adult laryngeal mucosa. (7)

There is a frustrating lack of clarity as to what constitutes an adenocarcinoma of the larynx once an adenoid cystic carcinoma has been ruled out. From the literature, one gets the distinct impression that these so-called adenocarcinomas are poorly differentiated, large, bulky, and usually supraglottic neoplasms of subsurface origin. (7) None of the tumor areas in our patient contained the basement membrane material that is characteristic of adenoid cystic carcinomas.

The case of our patient is an example of morphologic mimicry, a well-known phenomenon seen in malignant human neoplasms during surgical pathology; both undifferentiated and "committed" neoplasms can exhibit this trait. (16) Ductal carcinomas of the salivary glands, breasts, and cutaneous appendages comprise one particularly common group of such histologic mimickers. Wick et al studied 103 tumors that featured this structural cluster and analyzed them microscopically arid immunohistologically to codify points of potential pathologic similarity and difference. (16) They found a statistically significant infrequency of gross cystic disease fluid protein-15 in eccrine sweat gland carcinomas, a paucity of carcinoembryonic antigen in breast cancers, and an absence of estrogen receptor protein in salivary duct carcinomas. These findings might be useful in establishing predefined differential diagnostic settings with regard to making a distinction between primary and metastatic ductal cancers of the breast, skin, an d salivary glands. The remarkable similarity in the microscopic features of salivary duct carcinomas and mammary duct carcinomas further raises questions as to whether these tumors share antigenic or hormonal features. Because of the striking homology of these tumors in terms of structure and protein synthesis, all available clinicopathologic information must be used in making a diagnosis. (16) Even so, Lewis et al found no hormonal concordance between salivary duct and breast carcinomas in their clinicopathologic and immunohistochemical review of 26 cases of salivary duct carcinoma that had arisen from the parotid and submaxillary glands. (10) In our patient, we ruled out the possibility that the laryngeal mass represented a metastasis of a sweat gland, prostate, or mammary carcinoma via a thorough clinical history and examination.

The clinical and pathologic features of salivary duct carcinomas that might predict survival are not well delineated because of the scant amount of knowledge we have regarding this tumor's clinical behavior and natural history. Such predictors will not become more clear until more reports are accumulated in the literature.

References

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(16.) Wick MR. Ockner DM, Mills SE, et al. Homologous carcinomas of the breasts, skin, and salivary glands. A histologic and immunohistochemical comparison of ductal mammary carcinoma, ductal sweat gland carcinoma, and salivary duct carcinoma. Am J Clin Pathol 1998;109:75-84.

From the Department of Pathology (Dr. Goel and Dr. Srivastava) and the Department of Otolaryngology (Dr. Agrawal), King George's Medical College, Lucknow, Uttar Pradesh. India.

Reprint requests: Dr. M.M. Goel, Professor, Department of Pathology, King George's Medical College, Lucknow-226004, Uttar Pradesh, India. Phone: [phone]; fax: [phone]; e-mail: [e-mail].