Hyalinising clear cell carcinoma of the salivary gland, HCCC

This is an uncommon salivary gland tumour composed exclusively of clear cells containing abundant glycogen. It has been variously considered a form of clear cell adenocarcinoma or a variant of squamous cell carcinoma.

Clinical features

90% of cases involve minor intraoral salivary glands4, but rarely cases in the tongue, parotid gland and larynx have been reported.

Histopathology

The clear cells are arranged in trabeculae, cords, nests and sheets surrounded by a hyalinised PAS-positive stroma. The stroma may be focally myxoid. There is no glandular or ductal architecture. Mucin stains are negative4. The cells cytoplasm varies from clear to palely eosinophilic. Nuclei are slightly irregular. Nucleoli may be seen but are not prominent.

Immunohistochemistry

cytokeratin

positive1,4

AE1/AE3

1/15

CK7

1/15

CK20

0/15

EMA

positive1,4

CEA

focal positivity1

S-100

negative1,4

Calponin

negative1

SMA

negative1,4

Collagen I

stroma positive in 3/32

Collagen III

stroma positive in 2/32

Collagen IV

positive only around tumour cells, not in the interstitial stroma2

Laminin

positive only around tumour cells, not in the interstitial stroma2

Fibronectin

stroma positive in 3/32

Tenascin

positive in stroma at advancing front of the tumour2

   

Ultrastructure

There is abundant cytoplasmic glycogen. Desmosomes, peripheral tonofilaments and interdigitating microvilli are seen4. There may be basal lamina reduplication and large deposits of long space collagen2. There are no actin myofilaments to indicate myoepithelial differentiation.

Differential diagnosis

There are a number of primary salivary gland tumours which may have a clear cell appearance:

Prognosis

About 20% of cases have metastasised to neck lymph nodes. This is a low-grade malignancy with a recurrence rate of 17%. Pulmonary metastases may occur3 but no patient deaths have been reported.

References

Diagnostic histopathology of tumors. Edited by CDM Fletcher. 2nd edition. Churchill Livingstone. Page 283.

1 Perez-Ordonez B. Selected topics in salivary gland tumour pathology. Current Diagnostic Pathology 2003;9:355-365.

2 Felix, A., J. C. Rosa, et al. (2002). "Hyalinizing clear cell carcinoma of salivary glands: a study of extracellular matrix." Oral Oncol 38(4): 364-8.

3 Wang, B., M. Brandwein, et al. (2002). "Primary salivary clear cell tumors--a diagnostic approach: a clinicopathologic and immunohistochemical study of 20 patients with clear cell carcinoma, clear cell myoepithelial carcinoma, and epithelial-myoepithelial carcinoma." Arch Pathol Lab Med 126(6): 676-85.

4 Milchgrub, S., D. R. Gnepp, et al. (1994). "Hyalinizing clear cell carcinoma of salivary gland." Am J Surg Pathol 18(1): 74-82.

5 Meer S,Altini M. CK7+/CK20- immunoexpression profile is typical of salivary gland neoplasia. Histopathology 2007; 51:26-32

This page last revised 4.8.2007.

©SMUHT/PW Bishop