Adenoid cystic carcinoma of the salivary gland and its histologic variants A clinicopathologic
A
study
of thirty
cases
denoit1 cyst,itr cai~c.inoma of the salivary gland is a slow-growing tulnol which, if inatlequately excised, will recur, infiltrate locally, ancl not infrequently metastasize to regional lymph nodes or distant organs and cause death.*-’ The typical adenoid cystic carcinoma of salivary origin is composed of nests of uniform, dark-staining cells within which are cribriform spaces containing eosinophilic hyalinc material.‘! z IIomever, these tumors exhibit a wide spectrum of histologic aI)r)caranccs. inclutlimz some with a rcwmblanw to basal-cell carcinoma
Table I. Tumors of the salivary glands, 1952-1975 Tumor
NO.
Pleomorphic adenoma Adenoid cystic carcinoma Adenolymphoma Mucoepidermoid carcinoma Malignant mixed tumor Acinic-cell carcinoma Adenocarcinoma Monomorphic adenoma Undifferentiated carcinoma Oxyphil adenoma Papillary cystadenoma Total
distribution
238
Adenoid cystic carcinoma
30
III. Sites of origin
of thirty
45.2 (rang;,,\l-85)
I44
Pleomorphic adenoma Adenoid cystic carcinoma
89
12s
70
of adenoid cystic carcinomas and pleomorphic Site
type
Rote
Sex I F]M)C]W]R
31
(range 20-90)
Palate
Parotid Tumor
62.00 8.00 6.50 5.50 4.25 3.50 3.50 3.00 2.00 1.oo 0.75 100.00 -
adenoid cystic carcinomas and
Meun age at diagnosis (yr.)
No.
type
Pleomorphic adenoma*
Table
Per writ
32
Table II. Age, sex, arid racial pleomorphic adenomas Tumor
1
238 30 25 22 17 14 I? 11 7 4
of tumor Submandibular
Other
No.
No.
Per cent
238
I75
13.5
37
15.5
8
3.5
I9
7.5
30
II
37.0
9
30.0
5
16.5
5
16.5
No.
Per cent
adenomas
NO.
Per cent
NO.
Per cent
partment from 1952 to 1975, we noted that the diagnosis of adenoid cystic carcinoma had caused the most difficulty. This clinicopathologic study of thirty adenoid cystic carcinomas includes ultrastructural observations and an e.xamination of some of the staining reactions of the muck found in these tumors. MATERIALS
AND
METHODS
Ilematoxylin-and-eoskstained sections from 384 salivary gland tumors on rwctrtl in our surgit+aI pathology files over a 2-Ly;~r period, 1952 to 1975, wcrc reviewed. The thirty adenoid cystic carcinomas were select4 for further study. Sections wcrc recut anal stained with hematoxylin and eosin, periodic acitl-Schiff (PAS), al&n blue, mucic~arniinr~, and Jvcrhoeff’s hematoxylin elastic tissue stain. For electron microscopk examination, minced fragments of a rescc*ted tumor were immcdia.tel,v transferred to pl~ospha.tc-lluffered glutaraldehydc and postfixed in Palade’s solution. After tlehptlratioll in graclctl a(~ctonc, the tissue was embedded
T-olume 44 Nurnlw 3
Pig. 2. A hybrid tumor showing typical adenoid cystic pattern in right upper half of photomicrograph and basal-cell pattern in left lower half. Note the larger spaces in the former as compared to the smaller ductal spaces in the latter. (Hematoxylin and eosin stain. Magnification, x125.) Pig. B. A hybrid tumor. Note the thready material in spaces of the typical adenocytic area in right upper half of photomicrograph and intensely stained, coarsely granular, mucicarminophilic material in ductal spaces of basaloid area in left lower half of photomicrograph. (South gate’s mucicnrmine stain. Magnification, x320.)
did the fibrillar strands. While most of the spaces were completely surrounded by a mantle of cells of the myoepithelial type, occasional continuity between these spaces and the eonnectivc tissue stroma could be demonstrated. In a minority of cases, the connective tissue stroms had a hyalinized appearance. The small ducts described above contained coarsely granular or floccular material which was stained intensely by mucicarmine and PAS. An additional feature seen in several of these tumors was the presence in the stroma of ribbons of brightly eosinophilic elastic tissue. The basaloid type of adenoid cystic carcinoma was composed of solid islands
398
Nochomovitz
nud Knh )I
Oral Surg. September, 1977
Pig. 3. Two small ducts (arrows) lined with cells with more resicular nuclei are surrounded hy uniform stellato cells in a typical adenoid cystic carcinoma. (Hematoxylin and eosin stain. Magnification, x800.) Fig. 4. Close-set cells in a basaloid variant containing moderate: numbers of’ mitotic fiigurcs (arrows). (Hcmatoxylin and eosin stain. Magnification, x320.)
of cells with a resemblance to a basal-cell carcinoma (Figs. 1, 2, and 1). The\ were closely packect and had more hypcrchromatic nuclei and scantier cytoplasm than the cells in the typical adenoid cystic caarcinoma. Their ~11 membranes were ill-defined. Rtitoscs wcrc fairly numerous, and foci of tumor necrosis or necrosis of individual tumor ~11s wwc common. The cribriform SISKCS,although present,, were less conspicuous than in the typical adcnoicl cystie carcinoma and were smaller in size. This imparted to the lesion a more compact appcarancr and hence the resemblance to ;I basal-~11 carcinoma. These cd)-stic*spaces containctl floccular mucicarminophilic material (Fig. 2). The hybritl variety included tumors with islands of typical adenoid cyst,ic carcinoma and of the basaloid type of adenoid cystic carcinoma in juxtaposition ( h’igs. 1 and 2). Ultrastructural examination of a typical adcnoicl cystic carcinoma confirmed the presence of two types of spave. The more frequent ty!)cx cdontained numerous delicate filaments measuring about 10 to 15 nm. in diamctrr ant1 with a periodic structure (Figs. 5 and 6). This material corresponded to the thready material seen by light microscopy. At the periphery of the space, a layer of clcctron-lucent, basement-membrane-like material abutted on the plasma membrane of the sur-
2%~. ii. Electron mierograph showing space filled with delicate fibrillar material from the plasma. membrane by an electron-lucent layer of basement, membrane-like (Magnification, x9,500.)
separated material.
rounding cells of the myoepithelial type, and this corresponded to the homogeneous eosinophilic material in the sections stained with hematoxylin and eosin. The cells surrounding these spaces had smooth plasma membranes and were devoid by cells with disof tight junctions. The second type of space was SLmYJWKkd tinct microvilli and junctional complexes, as is typical of ductular cells (Fig. 7). The spaces formed by these cells contained electron-lucent, homogeneous nonfibrillar material with a few electron-dense particles. This corresponded to the coarsely granular eosinophilic material seen with the light microscope. In a few of the tumor cells, cytoplasmic filaments were observed. Some of these were delicate and random17 distributed (E’ig. 6), while others were coarser and aggregated to form tonofilamcnt bundles which participated in the formation of wellformed dcsmosomes ( Fig. 8). The average duration of symptoms prior to diagnosis was 7.6 years in the t-pica1 group hut only 1.7 and 1.X years in the basaloid and hybrid groups, respectively. Follow-up information was available in twenty-five of the thirt: cases. Ten patients died between 5 months and 10 years following diagnosis, with a mean follow-up of 30 months, and in at least six of these ten cases the tumor was largely responsible for death. Six patients had extensive local disease, four hacl clinical cvidencc of clistant mctastases (three to the lungs, one to the liver),
had histologically lrovcn regional node mctastases. The other fifteen patients were alive whtrn last see11and hacl been followed for periods of from :! months to IS years, with a mean f’ollowup of HI months. T~~levc~n of the fiftccll t11an1 3 ~(~i~YS. Ahout OIW half of t llese fifteen patients had been follo\vcd for mow had cvidence of persistent tumor when last seen. and two
DISCUSSION
The typical
adenoid cystic carcinoma has iteen recognized for more than II of the c~sistence of more aggrw sivc histologic variants is comparatively rcccnt.1-3. imC’In thesc variants, mow solid islands composed of dark basaloid ~11s with areas oi’ necrosis and increased mitotic activity arc prcwnt, cithcr alone or in combination with the typical cribriform or Swiss-cheese pattern.’ The diagnosis of the typical tumor is usually easy-, but in some cases it, may bc difficult to distinguish from a benign plcomorphic adcnoma. This con fusion is nsuallp the result of the presence of a hyalinc stroma and a cylindromatous patter11 iI1 areas of’ the plcomorphic adenoma.” (lonverscly, Thackral- and LucaS: have illustrated the accumulation of a mutinous material betnecn the tumor cells in parts of an adenoid cystic carcinoma, resultce1ltur.v under \-arious synonyms, but knonlcdgc
flohoid
Fig. 7. Electron micrograph showing and microvilli. (Magnification, x9,000.)
cystic carcinonm of sahivary glad
duct lined with
cells containing
junctional
401
complexes
ing in an appearance simulating pleomorphic adenoma. It is important to minimize errors in diagnosis by examining several blocks from different parts of the tumor. An important feature in the differentiation between these two tumors is the sharp separation of the cell nests from the connective tissue stroma in the adenoid cystic carcinoma and the gradual transition between the epithelial and stromal elements of the pleomorphic adenoma. The adenoid cystic carcinoma usually shows an infiltrative growth pattern at the margin of the tumor and perineural invasion, features not seen in pleomorphic aden0ma.l’ 3+ The cylindrical spaces of the adenoid cystic carcinoma may be filled with solid cores of hyaline material, a feature often considered of major diagnostic significance.‘O However, this hyaline material varies considerably, both qualitatively and quantitatively.2, 3, 5 In our study, the presence of solid hyaline cylinders was the exception rather than the rule; the spaces usually contained a few faint threads of weaklv eosinonhilic material. a thin nerinheral rim of hvaline base-
cells, and their behavior was no different from the typical adenoid cystic lesions. ( )thcrs have considered the clinical staging to have1 greater prognostic significance than histologic grading.” The presence in this series of six hybrid tumors iu which the typical and basaloid variants co-existed suggests that malignant tumors with a basaloid cell element, are, indeed, part of the spectrum of adenoid cystic carcinoma. It is perhaps relevant in this rcgartl that basal-cell adenoma has been considered as the benign homologue of adenoid cystic carcinoma and that some of the ultrastructural features of basal-cell adcnoma arc identical to those of adenoid cystic carciiloma.14~ I3 Our histochcmical studies confirm the findings of Azzopardi and Smith.lG The occasional small ducts within the typical tumor contain epithelial mucin, while the more numerous cylindrical spaces contain a connective tissue mucin. The basaloid variants tend to produce more epithelial mu& than do the typical tumors, suggesting a greater differentiation toward cells of t.hc ductal secretor! t,ype rather than of the myoepthelial type. Ultrastructurally, the presence of two distinct types of extracellular space, was confirmed. One corresponded to the epithclium-lined ducts and the other to the cylinders surrounded by cells of the myoepithelial type. The ultrastructural studies of Hoshino ant1 Yamamoto,17 Koss and co-workers,ls and Tandler’” demonstrated similar features. Koss and colleagues’S noted that the basement-membrane-like material at the periphery of the cylinders consists of an inner lamina densa and an outer lamina lucida. In our case, an outer, more electron-lucent zone was also seen, but frequently there was direct contact l~tt~cen the inner dcnsc~ layer and the plasma membrane of the surrounding cells. TandleP tlcmonstratetl that the basal lamina may he highly replicated am1 that the delicate fibrils arc frcyuently arrayed concentrically within intcrstices of this multilaminar basement mrmhranc. Chenzu also demonstrated replication of the basal Iamina and notctl an intermediate zone composed of tiny stellatc granules of mucoitl lllilt~rkl ant1 R central core c~omposd 0-f cloS?l~ packed bundles of finr filaments or mature collagen fibrils. Our electron microscopic study tlcmonstratc~l two ccl1 types comprising the typical tumor, namely, il tluctal cell containing numerous microvilli and ,junctional complexes and more numerous cells of the mvoepithelial t,rpe dcroicl of microvilli. ITomerer, only a few of the latter contained delicate’ cytoplasmic filaments and an occasional
.-
.= 1s
-7
.- 1 .r.
C!
.c
5;
ti.
-
A
study
of thirty
cases
denoit1 cyst,itr cai~c.inoma of the salivary gland is a slow-growing tulnol which, if inatlequately excised, will recur, infiltrate locally, ancl not infrequently metastasize to regional lymph nodes or distant organs and cause death.*-’ The typical adenoid cystic carcinoma of salivary origin is composed of nests of uniform, dark-staining cells within which are cribriform spaces containing eosinophilic hyalinc material.‘! z IIomever, these tumors exhibit a wide spectrum of histologic aI)r)caranccs. inclutlimz some with a rcwmblanw to basal-cell carcinoma
Table I. Tumors of the salivary glands, 1952-1975 Tumor
NO.
Pleomorphic adenoma Adenoid cystic carcinoma Adenolymphoma Mucoepidermoid carcinoma Malignant mixed tumor Acinic-cell carcinoma Adenocarcinoma Monomorphic adenoma Undifferentiated carcinoma Oxyphil adenoma Papillary cystadenoma Total
distribution
238
Adenoid cystic carcinoma
30
III. Sites of origin
of thirty
45.2 (rang;,,\l-85)
I44
Pleomorphic adenoma Adenoid cystic carcinoma
89
12s
70
of adenoid cystic carcinomas and pleomorphic Site
type
Rote
Sex I F]M)C]W]R
31
(range 20-90)
Palate
Parotid Tumor
62.00 8.00 6.50 5.50 4.25 3.50 3.50 3.00 2.00 1.oo 0.75 100.00 -
adenoid cystic carcinomas and
Meun age at diagnosis (yr.)
No.
type
Pleomorphic adenoma*
Table
Per writ
32
Table II. Age, sex, arid racial pleomorphic adenomas Tumor
1
238 30 25 22 17 14 I? 11 7 4
of tumor Submandibular
Other
No.
No.
Per cent
238
I75
13.5
37
15.5
8
3.5
I9
7.5
30
II
37.0
9
30.0
5
16.5
5
16.5
No.
Per cent
adenomas
NO.
Per cent
NO.
Per cent
partment from 1952 to 1975, we noted that the diagnosis of adenoid cystic carcinoma had caused the most difficulty. This clinicopathologic study of thirty adenoid cystic carcinomas includes ultrastructural observations and an e.xamination of some of the staining reactions of the muck found in these tumors. MATERIALS
AND
METHODS
Ilematoxylin-and-eoskstained sections from 384 salivary gland tumors on rwctrtl in our surgit+aI pathology files over a 2-Ly;~r period, 1952 to 1975, wcrc reviewed. The thirty adenoid cystic carcinomas were select4 for further study. Sections wcrc recut anal stained with hematoxylin and eosin, periodic acitl-Schiff (PAS), al&n blue, mucic~arniinr~, and Jvcrhoeff’s hematoxylin elastic tissue stain. For electron microscopk examination, minced fragments of a rescc*ted tumor were immcdia.tel,v transferred to pl~ospha.tc-lluffered glutaraldehydc and postfixed in Palade’s solution. After tlehptlratioll in graclctl a(~ctonc, the tissue was embedded
T-olume 44 Nurnlw 3
Pig. 2. A hybrid tumor showing typical adenoid cystic pattern in right upper half of photomicrograph and basal-cell pattern in left lower half. Note the larger spaces in the former as compared to the smaller ductal spaces in the latter. (Hematoxylin and eosin stain. Magnification, x125.) Pig. B. A hybrid tumor. Note the thready material in spaces of the typical adenocytic area in right upper half of photomicrograph and intensely stained, coarsely granular, mucicarminophilic material in ductal spaces of basaloid area in left lower half of photomicrograph. (South gate’s mucicnrmine stain. Magnification, x320.)
did the fibrillar strands. While most of the spaces were completely surrounded by a mantle of cells of the myoepithelial type, occasional continuity between these spaces and the eonnectivc tissue stroma could be demonstrated. In a minority of cases, the connective tissue stroms had a hyalinized appearance. The small ducts described above contained coarsely granular or floccular material which was stained intensely by mucicarmine and PAS. An additional feature seen in several of these tumors was the presence in the stroma of ribbons of brightly eosinophilic elastic tissue. The basaloid type of adenoid cystic carcinoma was composed of solid islands
398
Nochomovitz
nud Knh )I
Oral Surg. September, 1977
Pig. 3. Two small ducts (arrows) lined with cells with more resicular nuclei are surrounded hy uniform stellato cells in a typical adenoid cystic carcinoma. (Hematoxylin and eosin stain. Magnification, x800.) Fig. 4. Close-set cells in a basaloid variant containing moderate: numbers of’ mitotic fiigurcs (arrows). (Hcmatoxylin and eosin stain. Magnification, x320.)
of cells with a resemblance to a basal-cell carcinoma (Figs. 1, 2, and 1). The\ were closely packect and had more hypcrchromatic nuclei and scantier cytoplasm than the cells in the typical adenoid cystic caarcinoma. Their ~11 membranes were ill-defined. Rtitoscs wcrc fairly numerous, and foci of tumor necrosis or necrosis of individual tumor ~11s wwc common. The cribriform SISKCS,although present,, were less conspicuous than in the typical adcnoicl cystie carcinoma and were smaller in size. This imparted to the lesion a more compact appcarancr and hence the resemblance to ;I basal-~11 carcinoma. These cd)-stic*spaces containctl floccular mucicarminophilic material (Fig. 2). The hybritl variety included tumors with islands of typical adenoid cyst,ic carcinoma and of the basaloid type of adenoid cystic carcinoma in juxtaposition ( h’igs. 1 and 2). Ultrastructural examination of a typical adcnoicl cystic carcinoma confirmed the presence of two types of spave. The more frequent ty!)cx cdontained numerous delicate filaments measuring about 10 to 15 nm. in diamctrr ant1 with a periodic structure (Figs. 5 and 6). This material corresponded to the thready material seen by light microscopy. At the periphery of the space, a layer of clcctron-lucent, basement-membrane-like material abutted on the plasma membrane of the sur-
2%~. ii. Electron mierograph showing space filled with delicate fibrillar material from the plasma. membrane by an electron-lucent layer of basement, membrane-like (Magnification, x9,500.)
separated material.
rounding cells of the myoepithelial type, and this corresponded to the homogeneous eosinophilic material in the sections stained with hematoxylin and eosin. The cells surrounding these spaces had smooth plasma membranes and were devoid by cells with disof tight junctions. The second type of space was SLmYJWKkd tinct microvilli and junctional complexes, as is typical of ductular cells (Fig. 7). The spaces formed by these cells contained electron-lucent, homogeneous nonfibrillar material with a few electron-dense particles. This corresponded to the coarsely granular eosinophilic material seen with the light microscope. In a few of the tumor cells, cytoplasmic filaments were observed. Some of these were delicate and random17 distributed (E’ig. 6), while others were coarser and aggregated to form tonofilamcnt bundles which participated in the formation of wellformed dcsmosomes ( Fig. 8). The average duration of symptoms prior to diagnosis was 7.6 years in the t-pica1 group hut only 1.7 and 1.X years in the basaloid and hybrid groups, respectively. Follow-up information was available in twenty-five of the thirt: cases. Ten patients died between 5 months and 10 years following diagnosis, with a mean follow-up of 30 months, and in at least six of these ten cases the tumor was largely responsible for death. Six patients had extensive local disease, four hacl clinical cvidencc of clistant mctastases (three to the lungs, one to the liver),
had histologically lrovcn regional node mctastases. The other fifteen patients were alive whtrn last see11and hacl been followed for periods of from :! months to IS years, with a mean f’ollowup of HI months. T~~levc~n of the fiftccll t11an1 3 ~(~i~YS. Ahout OIW half of t llese fifteen patients had been follo\vcd for mow had cvidence of persistent tumor when last seen. and two
DISCUSSION
The typical
adenoid cystic carcinoma has iteen recognized for more than II of the c~sistence of more aggrw sivc histologic variants is comparatively rcccnt.1-3. imC’In thesc variants, mow solid islands composed of dark basaloid ~11s with areas oi’ necrosis and increased mitotic activity arc prcwnt, cithcr alone or in combination with the typical cribriform or Swiss-cheese pattern.’ The diagnosis of the typical tumor is usually easy-, but in some cases it, may bc difficult to distinguish from a benign plcomorphic adcnoma. This con fusion is nsuallp the result of the presence of a hyalinc stroma and a cylindromatous patter11 iI1 areas of’ the plcomorphic adenoma.” (lonverscly, Thackral- and LucaS: have illustrated the accumulation of a mutinous material betnecn the tumor cells in parts of an adenoid cystic carcinoma, resultce1ltur.v under \-arious synonyms, but knonlcdgc
flohoid
Fig. 7. Electron micrograph showing and microvilli. (Magnification, x9,000.)
cystic carcinonm of sahivary glad
duct lined with
cells containing
junctional
401
complexes
ing in an appearance simulating pleomorphic adenoma. It is important to minimize errors in diagnosis by examining several blocks from different parts of the tumor. An important feature in the differentiation between these two tumors is the sharp separation of the cell nests from the connective tissue stroma in the adenoid cystic carcinoma and the gradual transition between the epithelial and stromal elements of the pleomorphic adenoma. The adenoid cystic carcinoma usually shows an infiltrative growth pattern at the margin of the tumor and perineural invasion, features not seen in pleomorphic aden0ma.l’ 3+ The cylindrical spaces of the adenoid cystic carcinoma may be filled with solid cores of hyaline material, a feature often considered of major diagnostic significance.‘O However, this hyaline material varies considerably, both qualitatively and quantitatively.2, 3, 5 In our study, the presence of solid hyaline cylinders was the exception rather than the rule; the spaces usually contained a few faint threads of weaklv eosinonhilic material. a thin nerinheral rim of hvaline base-
cells, and their behavior was no different from the typical adenoid cystic lesions. ( )thcrs have considered the clinical staging to have1 greater prognostic significance than histologic grading.” The presence in this series of six hybrid tumors iu which the typical and basaloid variants co-existed suggests that malignant tumors with a basaloid cell element, are, indeed, part of the spectrum of adenoid cystic carcinoma. It is perhaps relevant in this rcgartl that basal-cell adenoma has been considered as the benign homologue of adenoid cystic carcinoma and that some of the ultrastructural features of basal-cell adcnoma arc identical to those of adenoid cystic carciiloma.14~ I3 Our histochcmical studies confirm the findings of Azzopardi and Smith.lG The occasional small ducts within the typical tumor contain epithelial mucin, while the more numerous cylindrical spaces contain a connective tissue mucin. The basaloid variants tend to produce more epithelial mu& than do the typical tumors, suggesting a greater differentiation toward cells of t.hc ductal secretor! t,ype rather than of the myoepthelial type. Ultrastructurally, the presence of two distinct types of extracellular space, was confirmed. One corresponded to the epithclium-lined ducts and the other to the cylinders surrounded by cells of the myoepithelial type. The ultrastructural studies of Hoshino ant1 Yamamoto,17 Koss and co-workers,ls and Tandler’” demonstrated similar features. Koss and colleagues’S noted that the basement-membrane-like material at the periphery of the cylinders consists of an inner lamina densa and an outer lamina lucida. In our case, an outer, more electron-lucent zone was also seen, but frequently there was direct contact l~tt~cen the inner dcnsc~ layer and the plasma membrane of the surrounding cells. TandleP tlcmonstratetl that the basal lamina may he highly replicated am1 that the delicate fibrils arc frcyuently arrayed concentrically within intcrstices of this multilaminar basement mrmhranc. Chenzu also demonstrated replication of the basal Iamina and notctl an intermediate zone composed of tiny stellatc granules of mucoitl lllilt~rkl ant1 R central core c~omposd 0-f cloS?l~ packed bundles of finr filaments or mature collagen fibrils. Our electron microscopic study tlcmonstratc~l two ccl1 types comprising the typical tumor, namely, il tluctal cell containing numerous microvilli and ,junctional complexes and more numerous cells of the mvoepithelial t,rpe dcroicl of microvilli. ITomerer, only a few of the latter contained delicate’ cytoplasmic filaments and an occasional
.-
.= 1s
-7
.- 1 .r.
C!
.c
5;
ti.
-
