An" Otol RhinlLory"l1ol101:1992
PATHOLOGY CONSULTATION
NONSQUAMOUS CARCINOMAS OF THE LARYNX JOHN
MARIO A. LUNA, MD
G. BATSAKIS, MD
HOUSTON, TExAs
ADEL K. EL-NAGGAR, MD, PHD
Nonsquamous carcinomas make up fewer than 1% of all epithelial malignancies ofthe larynx. The majority are subsurface in origin and arise from seromucous glands ofthe larynx. Adenoid cystic carcinoma is not only representative ofthis group, it is the most prevalent. All other salivary-type carcinomas are rare. Rarer still are surface adenocarcinomas. Neuroendocrine carcinomas appear to constitute the majority of so-called laryngeal adenocarcinomas.
and the following is derived from their studies.?'? There is an increase in the median gland count from the subglottis, to over the glottis, to the supraglottis: 263,271, and 371, respectively. The subglottic glands extend anteriorly and posteriorly from the lower border of the cricoid cartilage, without any differences in transition from the trachea, cranially up to the most medially prominent part of the vocal cord. The glottic area shows a considerable variation in gland count. The highest numbers are in the floor of the sinus ofMorgagni and in the false vocal cord. The lowest count is in the true vocal cord. The presence of glands centrally on the surface of the vocal cords is rare. Glands are found quite anterior in the anterior commissure or posteriorly toward the arytenoid region. In the supraglottis, the greatest number of glands are in the false cords, the aryepiglottic region, and, anterior, at the caudal part of the epiglottis. The aryepiglottic folds and the most cranial part of the epiglottis contain the fewest glands.
No more than 1% ofthe epithelial malignancies of the larynx are nonsquamous in type (Table 11-6). This low incidence makes them even less common than their counterparts in the sinonasal tract. Like those higher in the airway, the neoplasms can be imperfectly separated into ones that are surface and ones that are nonsurface (seromucous gland) in origin. In the larynx, the subsurface carcinomas outnumber the surface-origin nonsquamous carcinomas by a very considerable margin, with adenoid cystic carcinoma the most frequent and most readily recognized. The histologic equivalent of the papillary low-grade surface adenocarcinoma of the paranasal sinuses must be exceedingly rare. The present authors have never seen one.
SUBEPITHELIAL AND INTRAEPITHELIAL GLANDS The sites oforigin ofthe nonsquamous carcinomas of the larynx follow the anatomic distribution of the larynx's subepithelial glands and the intraepithelial mucous glands. Approximately two thirds of the adenoid cystic carcinomas are in the subglottis. The other nonsquamous carcinomas, in contrast, are rarely subglottic, with supraglottic and trans glottic involvement being nearly equal.
The overall density ofglands in the intrinsic larynx has been estimated to be between 23 and 47 glands per square centimeter. The lower part of the glottic region shows the greatest differences in density: 13 TABLE 1. NONSQUAMOUS CARCINOMAS OF LARYNX No.of No.of Laryngeal
The subepithelial glands are part ofthe mucociliary system of the laryngeal mucosa and are either purely mucous (usually small and tubular) or larger and branched tubuloalveolar seromucous glands. Secretory end-pieces are asymmetrically arranged around the duct system.
Authors Whicker et all Spiro et al 2 Ferlit03 Sessions et al4 Eschwege et al s Cohen et al 6
The number, distribution, and density ofthe glands in macroscopically normal adult laryngeal mucosae have been described by Bak-Pedersen and Nielsen,
Total
Laryngeal Nonsquamous Neoplasms Carcinomas % 0.9 27 3,100 0.5 2,793 14 2,052 1.0 21 888 1,342 2,967 13,142
9 5
18
94
0.1 0.4 0.6 0.7
From the Universityof Texas M. D. AndersonCancerCenter, Houston,Texas. REPRINTS - John G. Batsakis,MD, Dept of Pathology, Universityof Texas M. D. AndersonCancerCenter, 1515HolcombeBlvd, Houston,TX 77030.
1024
Batsakis et al, Pathology Consultation TABLE 2. "ADENOCARCINOMA" AND ADENOID CYSTIC CARCINOMA OF LARYNX
Characteristic No. of patients Male to female ratio Age at diagnosis (y) Location Supraglottis Subglottis rn~b
Transglottic Metastases to cervical lymph nodes at first presentation Death because of carcinoma Average survival of patients dying of carcinoma (mo)
"Adenocarcinoma" 50 1:11 46-80 (mean 63)
Adenoid Cystic Carcinoma 33 3:1 29-75 (mean 48)
37 8
11 18
5
2
0
2
30 (60%)
6 (18%)
33 (66%)
9 (27%)
17.5 (range 3-69)
49.4 (range 12-79)
Cases collected from references 1,2,5,6, 12-18.
glands per square centimeter on the vocal cords to 128per square centimeter on the false vocal cords and medial wall of Morgagni's sinus. The greatest concentration of glands is in the saccule (139 glands per square centimeter), and this region is also the one with the greatest median density (82 glands per square centimeter). There is a very low density of glands in the extrinsic laryngeal regions (epiglottic vallecula, pyriform recess, postcricoid region), with the valleculae and pyriform recess having the most constant occurrence and density. Intraepithelial glands are distinct from subepithelial glands. A typical intraepithelial gland is made up of 15 to 30 mucus-secreting cells with a structure like that of goblet cells. They extend from the epithelial surface down toward the basement membrane, on which they may rest, but which they do not penetrate. The cells are radially placed around a narrow lumen that extends to the epithelial surface, where it debouches in a narrow stoma. Irregularly distributed in the larynx, intraepithelial glands are most numerous in the supraglottis and least numerous in the subglottis. In any laryngeal region the glandular areas meaSure from 0.25 to 60 mm- (median 4 mm-). There is a significant negative correlation between the occurrence ofintraepithelial glands and that of subepithelial glands in the supraglottis. NONSQUAMOUS CARCINOMAS
Except for adenoid cystic carcinomas, salivarytype carcinomas are rare in the larynx. Even pleomorphic adenomas are almost curiosities in the larynx. Immunocytochemical methods have now appropriately classified as neuroendocrine neoplasms
1025
many types formerly included under the generic heading of adenocarcinoma.l'' These in turn are subtyped as typical or atypical carcinoids and small cell neuroendocrine carcinomas.P For mucopidermoid carcinomas, there are no specific techniques to help establish the diagnosis. Pathologists have to rely on subjective interpretations based on a histologic similarity to mucoepidermoid carcinomas of the major and oral salivary glands, a taxonomically ambiguous intracellular mucin, or worse, extracellular mucoid changes to support a diagnostic impression. The finding of mucin within cells of a mucosal or submucosal neoplasm is not enough to frame a diagnosis of mucoepidermoid carcinoma. Damiani et alII have suggested there is a continuum of laryngeal surface carcinomas: 1) nonmucin-producing squamous cell carcinoma, 2) squamous cell carcinoma with unicellular mucin production, 3) mucoepidermoid-adenosquamous carcinoma, 4) adenocarcinoma with variable degrees of squamous metaplasia, and 5) pure adenocarcinoma. The combining of mucoepidermoid carcinoma with adenosquamous carcinoma reflects the difficulty surgical pathologists have in distinguishing between these two carcinomas in mucosae. Even considering the two carcinomas as a diagnostic unit, it is evident that they are uncommon neoplasms in the larynx. In their report of 21 mucoepidermoid-adenosquamous carcinomas from the Armed Forces Institute of Pathology (AFIP) files of 1945 to 1979, Damiani et al ll indicated there had been only 32 previously reported cases in the world's literature.
If the histologic appearances permit, it is important to separate the mucoepidermoid-adenosquamous carcinoma group into high and low grades because ofthe marked differences in prognosis. Eight of the 21 AFIP neoplasms were called low-grade mucoepidermoid carcinomas. (The descriptions and photomicrographs are appropriate.) Nine, according to the authors, were more appropriately considered adenosquamous carcinomas than mucoepidermoid carcinomas. By an actuarial method, the 3-, 5-, and 10year survival for all ofthelow-grade mucoepidermoid carcinomas was 100%, regardless ofclinical stage (6 of the 8 were stage 1 or 2). For the adenosquamoushigh-grade mucoepidermoid carcinomas, the survival followed clinical stage and grade, and was 53% at 3 years posttherapy. On the basis of our own experience and that of the AFIP, it is safe to presume that except for low-grade mucoepidermoid carcinomas, other supposed grades
1026
Batsakis et al, Pathology Consultation
of that carcinoma in the larynx are much more likely to be adenosquamous carcinomas.
differentiated adenocarcinoma in the deep parts of the neoplasm.
The requirement for an adenocarcinoma and a squamous cell carcinoma to be present in the same neoplasm with readily light-optic demonstrable intercellular bridges and keratinization in the squamous carcinoma component should reduce possible confusion with mucoepidermoid carcinoma. A nearly constant presence of an in situ or superficial squamous cell carcinoma also points to an adenosquamous carcinoma. Adenosquamous carcinomas have the property of involving the surface mucosa, an ability rarely seen in mucoepidermoid carcinomas. Adenosquamous carcinomas are usually deeply invasive and manifest a decided tendency to shed their squamous phenotype and to become more like a poorly
There is also a frustrating lack of clarity in what constitutes an "adenocarcinoma" of the larynx after exclusion of adenoid cystic carcinoma. From the literature one gets the distinct impression that the socalled adenocarcinomas are poorly differentiated, large, bulky, and preponderantly supraglottic neoplasms that are subsurface in origin. When photomicrographic illustrations are available, many, if not most, have a neuroendocrine appearance. At the risk of comparing "apples and oranges," we present in Table 2 1,2,5,6,12-18 data on laryngeal adenocarcinomas and adenoid cystic carcinomas. 12-18 We have excluded tumors labeled mucoepidermoid or adenosquamous carcinoma from the adenocarcinoma group.
REFERENCES 1. Whicker JH, Nee1 HB m, Weiland LH, Devine KD. Adenocarcinoma of the larynx. Ann Otol Rhinol Laryngol 1974;83:487-90. 2. Spiro RH, Lewis JS, Hajdu SI, Strong EW. Mucus gland tumors of the larynx and laryngopharynx. Ann Otol Rhinol LaryngoI1976;85:498-503. 3. Ferlito A. Histological classification of larynx and hypopharynx cancers and their clinical implications. Pathologic aspects of 2052 malignant neoplasms diagnosed at the ORL Department of Padua University from 1966 to 1976. Acta Otolaryngol [Suppl] (Stockh) 1976(suppI342). 4. Sessions 00, Murray JP, Bauer WC, Ogura JA. Adenocarcinoma of the larynx. Can J OtolaryngoI1975;4:293-6. 5. Eschwege F, Cachin Y, Micheau C. Treatment of adenocarcinomas of the larynx. Can J OtolaryngoI1975;4:290-2. 6. Cohen J, Guillamondegui OM, Batsakis JG, Medina JE. Cancer of the minor salivary glands of the larynx. Am J Surg 1985;150:513-8. 7. Bak-Pedersen K.Nielsen KO. Subepithelial mucous glands in the adult human larynx. Studies on number, distribution and density. Acta Otolaryngol (Stockh) 1986;102:341-52. 8. Nielsen KO, Bak-Pedersen K. Intra-epithelial mucous glands in the adult human laryngeal mucosa. Acta Otolaryngol (Stockh) 1985;100:470-6. 9. Nielsen KO. Morphology of the subepithelial mucous glands in the adult human larynx. Acta Otolaryngol [Suppl]
(Stockh) 1988(suppl449):109-14. 10. Batsakis JO, EI-Naggar AK, Luna MA. Neuroendocrine tumors of the larynx. Ann Otol Rhinol LaryngoI1992;10l:71O4. 11. Damiani 1M, Damiani KK, Hauck K, Hyams VJ. Mucoepidermoid-adenosquamous carcinoma of the larynx and hypopharynx: a report of 21 cases and a review of the literature. Otolaryngol Head Neck Surg 1981;89:235-43. 12. Bloom J, Behar AJ, Zikk D, Shanon E. Adenocarcinoma of the epiglottis. Report of a case and review of the literature. Arch Otolaryngo1 Head Neck Surg 1987;113: 1330-3. 13. Cady B, Rippey JH, Frazell EL. Non-epidermoid cancer of the larynx. Ann Surg 1968;167:116-20. 14. HouleJA,JosephP, BatsakisJG. Primary adenocarcinomas of the larynx. J Laryngol Otol 1976;90: 1159-63. 15. Dallachy R. Adenoid-cystic carcinoma of the larynx. J LaryngolOtoI1969;83:1013-21. 16. Toomey 1M. Adenocarcinoma of the larynx. Laryngoscope 1967;77:931-61. 17. Olofsson J, van Nostrand AWP. Adenoid cystic carcinoma of the larynx. A report of four cases and a review of the literature. Cancer 1977;40:1307-13. 18. Ferlito A, Caruso G. Biological behavior of laryngeal adenoid cystic carcinoma. ORL J Otorhinolaryngol Relat Spec 1983;45:245-56.
PATHOLOGY CONSULTATION
NONSQUAMOUS CARCINOMAS OF THE LARYNX JOHN
MARIO A. LUNA, MD
G. BATSAKIS, MD
HOUSTON, TExAs
ADEL K. EL-NAGGAR, MD, PHD
Nonsquamous carcinomas make up fewer than 1% of all epithelial malignancies ofthe larynx. The majority are subsurface in origin and arise from seromucous glands ofthe larynx. Adenoid cystic carcinoma is not only representative ofthis group, it is the most prevalent. All other salivary-type carcinomas are rare. Rarer still are surface adenocarcinomas. Neuroendocrine carcinomas appear to constitute the majority of so-called laryngeal adenocarcinomas.
and the following is derived from their studies.?'? There is an increase in the median gland count from the subglottis, to over the glottis, to the supraglottis: 263,271, and 371, respectively. The subglottic glands extend anteriorly and posteriorly from the lower border of the cricoid cartilage, without any differences in transition from the trachea, cranially up to the most medially prominent part of the vocal cord. The glottic area shows a considerable variation in gland count. The highest numbers are in the floor of the sinus ofMorgagni and in the false vocal cord. The lowest count is in the true vocal cord. The presence of glands centrally on the surface of the vocal cords is rare. Glands are found quite anterior in the anterior commissure or posteriorly toward the arytenoid region. In the supraglottis, the greatest number of glands are in the false cords, the aryepiglottic region, and, anterior, at the caudal part of the epiglottis. The aryepiglottic folds and the most cranial part of the epiglottis contain the fewest glands.
No more than 1% ofthe epithelial malignancies of the larynx are nonsquamous in type (Table 11-6). This low incidence makes them even less common than their counterparts in the sinonasal tract. Like those higher in the airway, the neoplasms can be imperfectly separated into ones that are surface and ones that are nonsurface (seromucous gland) in origin. In the larynx, the subsurface carcinomas outnumber the surface-origin nonsquamous carcinomas by a very considerable margin, with adenoid cystic carcinoma the most frequent and most readily recognized. The histologic equivalent of the papillary low-grade surface adenocarcinoma of the paranasal sinuses must be exceedingly rare. The present authors have never seen one.
SUBEPITHELIAL AND INTRAEPITHELIAL GLANDS The sites oforigin ofthe nonsquamous carcinomas of the larynx follow the anatomic distribution of the larynx's subepithelial glands and the intraepithelial mucous glands. Approximately two thirds of the adenoid cystic carcinomas are in the subglottis. The other nonsquamous carcinomas, in contrast, are rarely subglottic, with supraglottic and trans glottic involvement being nearly equal.
The overall density ofglands in the intrinsic larynx has been estimated to be between 23 and 47 glands per square centimeter. The lower part of the glottic region shows the greatest differences in density: 13 TABLE 1. NONSQUAMOUS CARCINOMAS OF LARYNX No.of No.of Laryngeal
The subepithelial glands are part ofthe mucociliary system of the laryngeal mucosa and are either purely mucous (usually small and tubular) or larger and branched tubuloalveolar seromucous glands. Secretory end-pieces are asymmetrically arranged around the duct system.
Authors Whicker et all Spiro et al 2 Ferlit03 Sessions et al4 Eschwege et al s Cohen et al 6
The number, distribution, and density ofthe glands in macroscopically normal adult laryngeal mucosae have been described by Bak-Pedersen and Nielsen,
Total
Laryngeal Nonsquamous Neoplasms Carcinomas % 0.9 27 3,100 0.5 2,793 14 2,052 1.0 21 888 1,342 2,967 13,142
9 5
18
94
0.1 0.4 0.6 0.7
From the Universityof Texas M. D. AndersonCancerCenter, Houston,Texas. REPRINTS - John G. Batsakis,MD, Dept of Pathology, Universityof Texas M. D. AndersonCancerCenter, 1515HolcombeBlvd, Houston,TX 77030.
1024
Batsakis et al, Pathology Consultation TABLE 2. "ADENOCARCINOMA" AND ADENOID CYSTIC CARCINOMA OF LARYNX
Characteristic No. of patients Male to female ratio Age at diagnosis (y) Location Supraglottis Subglottis rn~b
Transglottic Metastases to cervical lymph nodes at first presentation Death because of carcinoma Average survival of patients dying of carcinoma (mo)
"Adenocarcinoma" 50 1:11 46-80 (mean 63)
Adenoid Cystic Carcinoma 33 3:1 29-75 (mean 48)
37 8
11 18
5
2
0
2
30 (60%)
6 (18%)
33 (66%)
9 (27%)
17.5 (range 3-69)
49.4 (range 12-79)
Cases collected from references 1,2,5,6, 12-18.
glands per square centimeter on the vocal cords to 128per square centimeter on the false vocal cords and medial wall of Morgagni's sinus. The greatest concentration of glands is in the saccule (139 glands per square centimeter), and this region is also the one with the greatest median density (82 glands per square centimeter). There is a very low density of glands in the extrinsic laryngeal regions (epiglottic vallecula, pyriform recess, postcricoid region), with the valleculae and pyriform recess having the most constant occurrence and density. Intraepithelial glands are distinct from subepithelial glands. A typical intraepithelial gland is made up of 15 to 30 mucus-secreting cells with a structure like that of goblet cells. They extend from the epithelial surface down toward the basement membrane, on which they may rest, but which they do not penetrate. The cells are radially placed around a narrow lumen that extends to the epithelial surface, where it debouches in a narrow stoma. Irregularly distributed in the larynx, intraepithelial glands are most numerous in the supraglottis and least numerous in the subglottis. In any laryngeal region the glandular areas meaSure from 0.25 to 60 mm- (median 4 mm-). There is a significant negative correlation between the occurrence ofintraepithelial glands and that of subepithelial glands in the supraglottis. NONSQUAMOUS CARCINOMAS
Except for adenoid cystic carcinomas, salivarytype carcinomas are rare in the larynx. Even pleomorphic adenomas are almost curiosities in the larynx. Immunocytochemical methods have now appropriately classified as neuroendocrine neoplasms
1025
many types formerly included under the generic heading of adenocarcinoma.l'' These in turn are subtyped as typical or atypical carcinoids and small cell neuroendocrine carcinomas.P For mucopidermoid carcinomas, there are no specific techniques to help establish the diagnosis. Pathologists have to rely on subjective interpretations based on a histologic similarity to mucoepidermoid carcinomas of the major and oral salivary glands, a taxonomically ambiguous intracellular mucin, or worse, extracellular mucoid changes to support a diagnostic impression. The finding of mucin within cells of a mucosal or submucosal neoplasm is not enough to frame a diagnosis of mucoepidermoid carcinoma. Damiani et alII have suggested there is a continuum of laryngeal surface carcinomas: 1) nonmucin-producing squamous cell carcinoma, 2) squamous cell carcinoma with unicellular mucin production, 3) mucoepidermoid-adenosquamous carcinoma, 4) adenocarcinoma with variable degrees of squamous metaplasia, and 5) pure adenocarcinoma. The combining of mucoepidermoid carcinoma with adenosquamous carcinoma reflects the difficulty surgical pathologists have in distinguishing between these two carcinomas in mucosae. Even considering the two carcinomas as a diagnostic unit, it is evident that they are uncommon neoplasms in the larynx. In their report of 21 mucoepidermoid-adenosquamous carcinomas from the Armed Forces Institute of Pathology (AFIP) files of 1945 to 1979, Damiani et al ll indicated there had been only 32 previously reported cases in the world's literature.
If the histologic appearances permit, it is important to separate the mucoepidermoid-adenosquamous carcinoma group into high and low grades because ofthe marked differences in prognosis. Eight of the 21 AFIP neoplasms were called low-grade mucoepidermoid carcinomas. (The descriptions and photomicrographs are appropriate.) Nine, according to the authors, were more appropriately considered adenosquamous carcinomas than mucoepidermoid carcinomas. By an actuarial method, the 3-, 5-, and 10year survival for all ofthelow-grade mucoepidermoid carcinomas was 100%, regardless ofclinical stage (6 of the 8 were stage 1 or 2). For the adenosquamoushigh-grade mucoepidermoid carcinomas, the survival followed clinical stage and grade, and was 53% at 3 years posttherapy. On the basis of our own experience and that of the AFIP, it is safe to presume that except for low-grade mucoepidermoid carcinomas, other supposed grades
1026
Batsakis et al, Pathology Consultation
of that carcinoma in the larynx are much more likely to be adenosquamous carcinomas.
differentiated adenocarcinoma in the deep parts of the neoplasm.
The requirement for an adenocarcinoma and a squamous cell carcinoma to be present in the same neoplasm with readily light-optic demonstrable intercellular bridges and keratinization in the squamous carcinoma component should reduce possible confusion with mucoepidermoid carcinoma. A nearly constant presence of an in situ or superficial squamous cell carcinoma also points to an adenosquamous carcinoma. Adenosquamous carcinomas have the property of involving the surface mucosa, an ability rarely seen in mucoepidermoid carcinomas. Adenosquamous carcinomas are usually deeply invasive and manifest a decided tendency to shed their squamous phenotype and to become more like a poorly
There is also a frustrating lack of clarity in what constitutes an "adenocarcinoma" of the larynx after exclusion of adenoid cystic carcinoma. From the literature one gets the distinct impression that the socalled adenocarcinomas are poorly differentiated, large, bulky, and preponderantly supraglottic neoplasms that are subsurface in origin. When photomicrographic illustrations are available, many, if not most, have a neuroendocrine appearance. At the risk of comparing "apples and oranges," we present in Table 2 1,2,5,6,12-18 data on laryngeal adenocarcinomas and adenoid cystic carcinomas. 12-18 We have excluded tumors labeled mucoepidermoid or adenosquamous carcinoma from the adenocarcinoma group.
REFERENCES 1. Whicker JH, Nee1 HB m, Weiland LH, Devine KD. Adenocarcinoma of the larynx. Ann Otol Rhinol Laryngol 1974;83:487-90. 2. Spiro RH, Lewis JS, Hajdu SI, Strong EW. Mucus gland tumors of the larynx and laryngopharynx. Ann Otol Rhinol LaryngoI1976;85:498-503. 3. Ferlito A. Histological classification of larynx and hypopharynx cancers and their clinical implications. Pathologic aspects of 2052 malignant neoplasms diagnosed at the ORL Department of Padua University from 1966 to 1976. Acta Otolaryngol [Suppl] (Stockh) 1976(suppI342). 4. Sessions 00, Murray JP, Bauer WC, Ogura JA. Adenocarcinoma of the larynx. Can J OtolaryngoI1975;4:293-6. 5. Eschwege F, Cachin Y, Micheau C. Treatment of adenocarcinomas of the larynx. Can J OtolaryngoI1975;4:290-2. 6. Cohen J, Guillamondegui OM, Batsakis JG, Medina JE. Cancer of the minor salivary glands of the larynx. Am J Surg 1985;150:513-8. 7. Bak-Pedersen K.Nielsen KO. Subepithelial mucous glands in the adult human larynx. Studies on number, distribution and density. Acta Otolaryngol (Stockh) 1986;102:341-52. 8. Nielsen KO, Bak-Pedersen K. Intra-epithelial mucous glands in the adult human laryngeal mucosa. Acta Otolaryngol (Stockh) 1985;100:470-6. 9. Nielsen KO. Morphology of the subepithelial mucous glands in the adult human larynx. Acta Otolaryngol [Suppl]
(Stockh) 1988(suppl449):109-14. 10. Batsakis JO, EI-Naggar AK, Luna MA. Neuroendocrine tumors of the larynx. Ann Otol Rhinol LaryngoI1992;10l:71O4. 11. Damiani 1M, Damiani KK, Hauck K, Hyams VJ. Mucoepidermoid-adenosquamous carcinoma of the larynx and hypopharynx: a report of 21 cases and a review of the literature. Otolaryngol Head Neck Surg 1981;89:235-43. 12. Bloom J, Behar AJ, Zikk D, Shanon E. Adenocarcinoma of the epiglottis. Report of a case and review of the literature. Arch Otolaryngo1 Head Neck Surg 1987;113: 1330-3. 13. Cady B, Rippey JH, Frazell EL. Non-epidermoid cancer of the larynx. Ann Surg 1968;167:116-20. 14. HouleJA,JosephP, BatsakisJG. Primary adenocarcinomas of the larynx. J Laryngol Otol 1976;90: 1159-63. 15. Dallachy R. Adenoid-cystic carcinoma of the larynx. J LaryngolOtoI1969;83:1013-21. 16. Toomey 1M. Adenocarcinoma of the larynx. Laryngoscope 1967;77:931-61. 17. Olofsson J, van Nostrand AWP. Adenoid cystic carcinoma of the larynx. A report of four cases and a review of the literature. Cancer 1977;40:1307-13. 18. Ferlito A, Caruso G. Biological behavior of laryngeal adenoid cystic carcinoma. ORL J Otorhinolaryngol Relat Spec 1983;45:245-56.
