Virchows Archiv

, Volume 449, Issue 2, pp 159–163

Preinvasive intraductal neoplasia in salivary adenocarcinoma, not otherwise specified

Authors

    • Institute of PathologyLudwig Maximilian University
  • Andrea Sendelhofert
    • Institute of PathologyLudwig Maximilian University
  • Christoph Weiler
    • Institute of PathologyLudwig Maximilian University
  • Hjalmar Hagedorn
    • Department of ENT, Head and Neck SurgeryLudwig Maximilian University
  • John D. Harrison
    • Department of Oral Pathology, King’s College London Dental Institute at Guy’sKing’s College and St. Thomas’ Hospitals
Original Article

DOI: 10.1007/s00428-006-0208-3

Cite this article as:
Ihrler, S., Sendelhofert, A., Weiler, C. et al. Virchows Arch (2006) 449: 159. doi:10.1007/s00428-006-0208-3

Abstract

Preinvasive intraductal neoplasia of the salivary glands has only been identified in the rare salivary-duct carcinoma, whereas, it is an established feature of carcinomas of other glands. A fortuitous observation of what appeared to be intraductal tumor in a salivary adenocarcinoma, not otherwise specified, led to the present investigation to determine whether intraductal neoplasia is a significant feature of this carcinoma. Intraductal tumor confined by normal CK14-positive, actin-negative ductal basal cells was identified in 15 of 22 cases (68%). The degree of cellular atypia and the pattern of growth of intraductal tumor was similar to that of the invasive tumor. Cases with intraductal tumor devoid of invasive tumor were not found. Intraductal tumor is identified as the pre-invasive precursor of adenocarcinoma, not otherwise specified, and apparently develops in excretory ducts. The findings support the possibility that different salivary tumors arise from different types of parenchymal cell. Possibly intraductal neoplasia is a universal feature of many types of salivary tumor, but has been overlooked because of the need to use immunohistology to demonstrate it and because it may no longer be present as such when the tumor presents as a clinical lesion.

Keywords

Salivary glandCarcinogenesisImmunohistochemistry

Introduction

Intraductal neoplasia has been identified as a precursor, preinvasive state of different types of invasive adenocarcinoma in many glands, such as the mammary gland, prostate, and pancreas [4, 5, 15, 18]. However, an intraductal component of adenocarcinomas of salivary glands has only been described in salivary duct carcinoma, which is rare [69, 20]. A fortuitous observation of what appeared to be intraductal tumor in a salivary adenocarcinoma, not otherwise specified, which is the second most common malignant tumor of the salivary glands [1, 17], led to the present investigation to determine whether preinvasive intraductal neoplasia is a significant feature of this tumor. Immunohistochemistry has been found to be of great value in identifying the cellular components of salivary glands in health and disease [8, 13, 14], and was, therefore, applied in the present investigation.

Materials and methods

Patients and tumor specimens

Surgical specimens from 22 cases of adenocarcinoma, not otherwise specified, were retrieved from the files from 1990 to 2004 of the Institute of Pathology, Ludwig Maximilian University, Munich. There were 15 males and seven females; the ages ranged from 39 to 80 years with an average of 63.5 years; and 18 tumors were located in the parotid and four in submandibular glands (Table 1). Sixteen of the 22 cases were part of an investigation into the value of different histochemical markers on the differential diagnosis of adenocarcinoma, not otherwise specified, and acinic cell carcinoma of salivary glands [12].
Table 1

Clinical and morphological features of salivary adenocarcinoma, not otherwise specified, with special reference to invasive and intraductal components

Case

Sex, age

Gland

pTN

Invasive tumor

Intraductal tumor

Histol. grade a

Pattern of growth

Proliferation (%)

Area (in %)

Histol. gradeb

Pattern of growth

Proliferation (%)

Necrosis

Extensionc (mm)

1

F64

P

pT2Nx

3

Sol

32.1

15

3

Sol

19.2

+

2

M50

P

pT2N2b

3

Sol

18.1

20

3

Sol

21.5

+

3

M60

S

pT2N0

3

Sol

25.4

10

3

Sol

27.0

+

4

M59

P

pT2N2b

3

Sol

29.3

5

3

Sol

15.6

+

1

5

M60

P

pT1N2b

2

Tub

8.0

d

     

6

M80

P

pT2N2b

3

Sol

11.7

5

2

Crib

9.8

7

F59

P

pT2N2b

2

Crib

11.9

25

2

Crib

23.3

+

8

F70

P

pT3N2b

3

Crib

4.4

d

9

M67

S

pT3N1

3

Sol

41.0

d

10

M64

P

pT1Nx

3

Sol

12.7

30

3

Sol

14.7

+

11

M52

P

pT1N2b

3

Sol

NE

d

     

12

F66

P

pT1N2b

3

Sol

13.3

d

     

13

F39

P

pT1N0

3

Sol

7.5

d

     

14

F66

P

pT4N1

3

Sol

38.9

10

3

Sol

28.6

+

4

15

M70

P

pT1Nx

3

Sol

18.7

40

3

Crib

29.9

+

3

16

M62

S

pT3N2b

3

Sol

15.3

2

3

Sol

-e

17

F78

P

pT1N0

2

Crib

18.2

5

2

Crib

12.2

5

18

M72

P

pT3N3

3

Sol

45.4

2

3

Crib

15.2

+

19

M63

S

pT3N2b

3

Sol

28.8

25

3

Sol

13.7

+

5

20

M64

P

pT4N0

3

Sol

32.0

2

2

Crib

-e

21

M69

P

pT4N2b

3

Sol

37.4

d

     

22

M62

P

pT2Nx

2

Crib

6.7

2

2

Crib

-e

M male, F female, P parotid, S submandibular gland, Sol solid, Tub tubular, Crib cribriform, NE not evaluable

aHistological grading of invasive tumor according to Auclair et al. [1];

bHistological grading of intraductal tumor according to Tavassoli et al. [18]

cExtension of intraductal tumor beyond area of invasive tumor (in mm)

dNo intraductal tumor found;

eIntraductal tumor component too small for accurate calculation of proliferation

The diagnosis of adenocarcinoma, not otherwise specified, was established according to the accepted structural and cytological criteria, which exclude more specifically characterized types of salivary adenocarcinoma [13, 10, 17, 20]. Clinical and histologic data were analyzed to exclude cases representing metastatic disease to the salivary glands or to intraparotid lymph nodes. On the basis of the TNM system [16] of 2002, seven cases were pT1, seven were pT2, five were pT3, and three were pT4; 14 cases had metastases to the lymph nodes (pN1,2,3) and four cases had no such metastases (pN0); and in four cases a neck dissection had not been performed (Table 1).

Histology and immunohistochemistry

The specimens had been fixed in 4% buffered formaldehyde and embedded in paraffin wax, and serial sections were cut at 4 μm. Modifications of the avidin–biotin complex method (ABC), the labeled streptavidin–biotin staining method (LSAB), and the alkaline-phosphatase anti-alkaline-phosphatase method (APAAP) were used. In accordance with previous studies of our group on the cellular composition of normal glands and glands with different reactive and neoplastic lesions [13, 14], antibodies for p63, α-actin and cytokeratin (CK) subtypes 7, 18, 14, and Ks8.12, and the proliferation-associated antibody Ki67 (MIB-1) were applied. Quantification of proliferation of the different cellular components was enabled by immunohistochemical double-staining for CK14 and Ki67 [13, 14]. Owing to the high level of endogenous biotin, especially in striated and excretory ductal cells, an avidin–biotin blocking system (DAKO Biotin Blocking System X0590) was added to the ABC and LSAB methods. Non-neoplastic salivary parenchyma served as a positive internal control.

Analysis

A combination of topographical, cytological, and immunohistological criteria was used to identify the different types of normal cell and the neoplastic cells in the salivary glands [1214]. Acinar cells were identified by positivity for CK18, intercalated ductal cells and columnar cells of striated and excretory ducts by positivity for CK7 and CK18, myoepithelial cells by positivity for α-actin, CK14, and p63, and basal cells by positivity for CK14, CK Ks8.12 and p63 (Fig. 2).

Analogous to tumor models of other glands [4, 5, 15, 18], intraductal tumor was defined as an intraductal expansion of cells with a variable degree of structural and cellular atypia and increased cellular proliferation that is confined by a continuous layer of regular basal or myoepithelial cells that are devoid of atypia. Owing to an absence of established criteria in salivary tumors, the WHO guidelines for histological grading of intraductal neoplasia in mammary glands were applied [18].

The cases were analyzed with respect to the following criteria: 1) area of intraductal tumor in comparison to the total invasive and intraductal area of tumor; 2) separate histological gradings of 1, low; 2, intermediate; and 3, high for intraductal tumor [18] and invasive tumor [1]; 3) identification of the predominant pattern of growth in intraductal tumor [18] and in invasive tumor [1] (solid, cribriform, or tubular); 4) separate quantifications of cellular proliferation for intraductal and invasive tumors; 5) presence of comedo-type necrosis and associated calcification in intraductal tumor; 6) extension of intraductal tumor beyond the area of invasive tumor; 7) localization of intraductal tumor in relation to the different parts of the salivary parenchyma.

Results

The presence of intraductal tumor could not be established in sections stained with hematoxylin and eosin in most cases; immunohistological staining, particularly with CK14, was necessary to identify and quantify the intraductal tumor within the quantitatively dominating invasive tumor (Fig. 1a1, 2). The intraductal tumors were mainly found in excretory ducts with normal basal cells that were positive for CK14, CK Ks8.12, and p63 and negative for α-actin (Figs. 1a1,b2,c1, 2). Both intraductal and invasive tumors were positive for CK7 and 18.
https://static-content.springer.com/image/art%3A10.1007%2Fs00428-006-0208-3/MediaObjects/428_2006_208_Fig1_HTML.gif
Fig. 1

Representative examples of intraductal neoplasia in adenocarcinoma, not otherwise specified. a1 Case 2 with a large component of intraductal tumour confined by CK14 positive basal cells (arrows) within invasive tumour (arrowheads). a2 Higher magnification of an adjacent section stained by haematoxylin and eosin shows the solid pattern and high degree of atypia, but the intraductal localization of tumour shown in a1 is not obvious. b1 Case 17 with a predominantly cribriform pattern both in invasive tumour (bottom: arrowheads) and in intraductal tumour in an excretory duct (top: arrows) that extends 5 mm beyond the invasive tumour, the junction of which was established in an adjacent section stained for CK14. b2 Higher magnification shows the cribriform pattern and intermediate grade atypia of the intraductal tumour that is confined by normal CK14 positive basal cells (arrows). c1 Case 14 with intraductal tumour in an excretory duct (arrows) with secondary ductal dilatation and surrounding acinar atrophy and chronic inflammation (arrowheads). c2 Higher magnification of CK14 Ki67 double staining shows solid intraductal tumour with high grade atypia and enhanced proliferation that is confined by normal CK14 stained basal cells without cellular atypia or enhanced proliferation (arrowheads)

https://static-content.springer.com/image/art%3A10.1007%2Fs00428-006-0208-3/MediaObjects/428_2006_208_Fig2_HTML.gif
Fig. 2

Schematic illustration of the proposed development of adenocarcinoma, not otherwise specified, (2) from preinvasive intraductal neoplasia (1)

Details of the intraductal and invasive tumors are shown in Table 1. Intraductal tumors were found in 15 of the 22 cases (68%). The amount of intraductal tumor in relation to the total area of tumor ranged from 2 to 40%, with an average of 13%. An extension of the intraductal tumor beyond the borders of the invasive tumor was found in five cases, with a maximum of 5 mm (Fig. 1b1,c1). There was no case of intraductal tumor without an invasive tumor. There were eight cases of solid intraductal tumor, which were all grade 3 with comedo-type necrosis in seven, and seven cases of cribriform intraductal tumor, two of which were grade 3 with comedo-type necrosis and five were grade 2 with comedo-type necrosis in one (Fig. 1b2,c2). Microcalcification was found in comedo-type necrosis in one case. Solid intraductal tumor was always associated with solid invasive tumor (Figs. 1a1, 2) and cribriform intraductal tumor was associated with solid invasive tumor in four cases and with cribriform invasive tumor in three cases (Figs. 1b1, 2). Grade 3 intraductal tumor was associated with grade 3 invasive tumor in all ten cases (Fig. 1a1, 2); and grade 2 intraductal tumor was associated with grade 3 invasive tumor in two cases and with grade 2 invasive tumor in three cases (Fig. 1b1, 2). The mean proliferation rate of intraductal tumors (Fig. 1c2) was 19.2%, with a minimum of 9.8% and a maximum of 29.9%, and was slightly lower than the 22.8% of invasive tumors.

Discussion

That immunohistological staining, especially for CK14, was usually necessary to demonstrate intraductal tumor and that it was demonstrated in 68% of all cases and occupied from 2 to 40% of the total tumor area indicates that it is probably present much more often than is realized in routinely prepared sections of adenocarcinoma, not otherwise specified. That cases with exclusively intraductal tumor were not found indicates that intraductal tumor of the salivary gland is symptomless. Unlike the situation in the breast, where intraductal tumor is detected radiologically in many cases owing to associated calcification in comedo-type necrosis [4, 18], there is a lack of calcification in the salivary adenocarcinoma, which possibly relates to a low level of calcium, as has been found in ductal cells of salivary glands and in pleomorphic adenoma [11].

The term intraductal neoplasia covers a group of atypical intraductal proliferations associated with an increased risk of development of invasive carcinoma. The intraductal neoplasia described in the present investigation is analogous to what is well-established in other glands, such as the mammary glands, pancreas, and prostate [4, 5, 15, 18, 19]. It appears to be a precursor, preinvasive state that develops in the ductal system, apparently in excretory ducts in adenocarcinoma, not otherwise specified (Fig. 2). The different cribriform and solid patterns of growth of this intraductal neoplasia correspond to the patterns of growth of the invasive carcinoma and also correspond to the patterns of growth of intraductal neoplasia of the mammary gland [18]. However, although the predominance of high-grade atypia in this salivary intraductal neoplasia corresponds to the usually high histological grade of invasive salivary adenocarcinoma, not otherwise specified, it contrasts to the coexistence of low-grade and high-grade variants of intraductal neoplasia of the mammary gland [18].

The only other salivary carcinoma in which intraductal neoplasia has been described is the salivary duct carcinoma, and this is mainly in the recently described rare variant with low-grade histology, which is termed ‘low-grade cribriform cystadenocarcinoma’ in the new WHO classification [2, 69, 20]. However, the intraductal neoplasm of salivary duct carcinoma has been reported to be confined by myoepithelial cells, which indicates a development from intercalated ducts, which normally contain myoepithelial cells [6, 7, 9, 20]. Whereas, the intraductal neoplasm of adenocarcinoma, not otherwise specified, described in the present investigation, is confined by normal basal cells in excretory ducts, which indicates a development from excretory ducts and, possibly, the basal cells that have been found capable of proliferation [13, 14, Fig. 2]. This difference is compatible with the possibility that different salivary tumors arise from different types of parenchymal cell rather than from a putative population of stem cells, as all the different types of parenchymal cell are capable of proliferation [13, 14].

The demonstration of an intraductal component may help to distinguish between primary and metastatic adenocarcinoma, which is a diagnostic problem more often encountered in the parotid, owing to relatively frequent metastases to intraparotid lymph nodes, as it is unlikely that a metastatic tumor would invade the parenchyma and extend into the ducts with the maintenance of the surrounding basal cells. The demonstration of extension of intraductal tumor up to 5 mm beyond the invasive tumor indicates how resection of a salivary adenocarcinoma could be incomplete and be followed by recurrence originating from persistent intraductal tumor, as can occur with mammary carcinoma [18].

Preinvasive intraductal neoplasia possibly occurs in many other types of salivary tumor, but has been overlooked because of the difficulty in establishing its presence in routinely stained sections and because continuing expansion of the invasive tumor destroys ducts so that intraductal tumor is no longer present as such. Thus, the application of the techniques used in the present investigation to other salivary tumors is necessary to investigate the possibility that intraductal neoplasia occurs in other types of salivary tumor.

Acknowledgement

This study was supported by a grant from the Friedrich-Baur-Stiftung, Munich, Germany (Grant no. 0016/2003).

Copyright information

© Springer-Verlag 2006