Cytopathology 1992,3,373-377
Acinic cell tumour: a metastasis in the lung diagnosed by electron microscopy of aspirated material J. M. M c C U T C H E O N , K. M A N C E R A N D I. D A R D I C K Divisions of Cytopathology and Electron Microscopy, Department of Pathology, The Toronto Hospital, Toronto General Hospital Division, Ontario, Canada Accepted for publication 30 June 1992
McCUTCHEON J. M., MANCER K. AND DARDICK 1.
(1992) Cytopathology 3,373-377
Acinic cell tumour: a metastasis in the lung diagnosed by electron microscopy of aspirated material
A case of acinic cell carcinoma, metastatic to lung is presented. Fine needle aspiration showed a low-grade adenocarcinoma. Electron microscopy of the aspirated material, however, allowed definite preoperative diagnosis of metastatic acinic cell carcinoma. The lesion was successfully resected and diagnosis confirmed on histology. Ten years previously an acinic cell carcinoma of similar histology had been excised from the left parotid region. Keywords: fine needle aspiration cytology, electron microscopy, salivary gland tumour, metastasis
INTRODUCTION Fine needle aspiration (FNA) is a most effective diagnostic technique that often avoids more invasive procedures. Ancillary diagnostic techniques such as immunocytochemistry or electron microscopy may be used on the specimens to clarify a diagnostic problem that cannot be resolved by conventional cytological preparations. We report a case in which electron microscopy of the aspirated material resulted in a confident preoperative diagnosis of metastatic acinic cell carcinoma. The diagnosis was confirmed on biopsy of the resected neoplasm. MATERIALS AND METHODS Case report A 69-year-old woman was found on chest X-ray to have a 2.5 cm mass in the right upper lobe. The lesion had been slowly increasing in size over 5 years. Ten years previously, she had a Correspondence: Dr J. M. McCutcheon, UMDS, Department of Histopathology, St Thomas’ Hospital, Lambeth Palace Road, London SEl7EH, UK.
374 J. M . McCutcheon, K. Mancer & I. Dardick
Figure 1. FNA of lung; cell block preparation. Some cytoplasmicgranularity in a well differentiated adenocarcinoma.Haematoxylin and eosin, x 400.
tumour mass resected from the left parotid region. This was shown to be mixed papillary and solid carcinoma. Electron microscopy of the tumour showed intracytoplasmic secretory material typical of the zymogen granules seen in an acinic cell carcinoma. One year later, a tumour mass was resected from subcutaneous tissue in the neck. This recurrent or metastatic tumour had a similar morphology to the original parotid lesion and an identical appearance on electron microscopy. The lung tumour was aspirated and following preoperative cytopathological and ultrastructural diagnosis, a right upper lobectomy was performed. Fluoroscopic-directed FNA of the lesion in the upper lobe of the right lung was performed. Aspirated material was immediately smeared on to glass slides, fixed in 95% alcohol and stained by the Papanicolaou method. A portion of the specimen was fixed in 2.5% gluteraldehyde and processed for electron microscopy. Further material was fixed in 50% alcohol, processed as a cell block, sectioned and then stained with haematoxylin and eosin and by the Papanicolaou method. RESULTS Cytopathology of FNA
Papanicolaou-stained smears were highly cellular, containing cohesive clusters of epithelial cells. The cells were monomorphic, with some clusters having a papillary configuration. The nuclei had a fine chromatin pattern and prominent nucleoli were seen in some cells (Figure 1).
Acinic cell carcinoma
315
Figure 2. (a) FNA of lung. Columnar cells with sparse surface microvilli and compact, densely staining zymogen-type secretory granules within the apical cytoplasm. (b) Resected (1980) parotid tumour. Tumour cells with an acinar-type arrangement and features similar to those of the FNA specimen. Uranyl acetate and lead citrate stain. (a) x 11 000, (b) x 4300.
The cytological appearances were suggestive of a low-grade adenocarcinoma. The differential diagnosis included broncholoalveolar carcinoma and low-grade papillary adenocarcinoma, possibly metastatic. The appearances did not suggest a classical acinic cell carcinoma. The tumour cells contained some weakly positive intracytoplasmic periodic acid-Schiff (PAS)-positive diastase resistant granules. Ultrastructure of FNA
Multiple fragments of well preserved tissue were present in the plastic sections cut from epon blocks. Ultrastructurally, tumour cells were cuboidal or columnar in shape, and had an orderly arrangement (Figure 2a). Adjacent cells were joined by well formed desmosomes. Many of the cells contained apical secretory granules with a homogeneous, darkly staining content; these secretory granules were of moderate and uniform size (Figure 2a). Typical
376 J . M . McCutcheon, K . Mancer & I. Dardick
Figure 3. Histology of the resected tumour with cuboidal and columnar cells forming a papillary adenocarcinoma.Haematoxylinand eosin, x 200.
mucous granules or secretory product with a lamellar configuration were not present. Both the organization of the tumour cells and their secretory product were comparable to the salivary gland tumour that had been resected 10 years before (Figure 2b). Light microscopy of resected tumour
Paraffin sections of the lung tumour showed a papillary adenocarcinoma consistent with acinic cell carcinoma (Figure 3 ) . The histology was similar to both the primary parotid gland carcinoma resected 10 years previously and the metastatic or recurrent subcutaneous lesion resected from the neck a year later. DISCUSSION Acinic cell carcinoma is a rare tumour accounting for approximately 3% of all salivary gland tumours. Metastases to cervical lymph nodes occur in 10% of cases, while metastases to lung and bone develop in approximately 15%’. The tumour has a highly variable morphology’-*. It may consist almost entirely of polygonal cells with granular, basophilic cytoplasm closely resembling normal serous acinar cells or these polygonal cells may be admixed with intercalated duct-like tumour cells; the latter are smaller than the polygonal cells and have acidophilic cytoplasm lacking the granularity of acinar-like cells. Rarely, the tumour cells are ofclear cell-type. The tumour may have a solid, trabecular, microcystic, follicular or papillary architecture. FNA cytology generally
Acinic cell carcinoma
371
results in a cellular smear3. The cells often have abundant foamy or granular cytoplasm. Typically PAS-positive diastase-resistant granules are present in tumour cells. The degree of differentiation of the acinar cells can make it difficult to categorize acinic cell carcinoma in FNA. This case highlights the use of electron microscopy of FNAs in diagnosing this rare type of metastatic adenocarcinoma in lung. A history of acinic cell carcinoma 10 years previously would not clinically preclude a diagnosis of a second primary tumour arising in lung. Radiologically the lesion could not be confidently diagnosed as either primary or metastatic. Adequate FNA material was available to establish a diagnosis of adenocarcinoma in the present case, but insufficient cytological details were present to decide whether the tumour was metastatic or represented a broncholoalveolar carcinoma. Although secretory granules were readily recognizable within the apical cytoplasm of the tumour cells, their numbers were insufficient to produce the cytoplasmic granularity required for an unequivocal diagnosis of acinic cell carcinoma. Furthermore, ultrastructurally the form and structure of the secretory granules were typical for zymogen4*’and could be distinguished from the various types of secretory cells, i.e. mucin, type I1 pneumocyte or Clara cells, that can be found in broncholoalveolar The ultrastructural characteristics of the FNA specimen led to a definite preoperative diagnosis of metastatic acinic cell carcinoma. In view of our experience with the adjunctive role of electron microscopy in FNAs7,*,we consider it prudent to save some aspirated material from deep-seated lesions for ultrastructural examination in case an unusually difficult diagnostic problem presents on light microscope examination of the specimen.
REFERENCES 1 Lewis JE, Olsen KD, Weiland LH. Acinic cell carcinoma-clinicopathologic review. Cancer 1991; 67: 172-9. 2 Ellis GL, Corio RL. Acinic cell adenocarcinoma: a clinicopathologic analysis of 294 cases. Cancer 1983; 52: 542-9. 3 Qizilbash AH, Young JEM. Salivary glands. In: Head and Neck, Guides to Ciinical Aspiration Biopsy. New York: Igaku-Shoin, 1988; 15-1 16. 4 Chaudhry AP, Cutler LS, Leifer C, Satchidanand S, Labay G, Yamane G. Histogenesis of acinic cell carcinoma of the major and minor salivary glands. Anultrastructural study. JPatholl986; 148:307-20. 5 Dardick I, George D, Jeans MTD, Wittkuhn JF, Skimming L, van Nostrand AWP. Ultrastructural
morphology and cellular differentiation in acinic cell carcinoma. Oral Surg 1987; 63:325-34. 6 Taccagni GL, Dell’Antonio G, Terreni MR, Cantaboni A. Heterogeneous subcellular morphology of lung adenocarcinoma cells;identification of different cytotypes on cytologic material. Ultrastruct Patholl990; 14 65-80. 7 Yazdi HM, Dardick I. ~mmuno~is~oche~iistry and Electron Microscopy, Guides to Clinical Aspiration Biopsy. New York: Igaku-Shoin, 1992. 8 Dardick I, Yazdi HM, Brosko C, Rippstein P, Hickey NM. A quantitative comparison of light and electron microscopic diagnoses in specimens obtained by fine needle aspiration biopsy. Uitrasiruct Pathol1991; 15: 105-26.
Acinic cell tumour: a metastasis in the lung diagnosed by electron microscopy of aspirated material J. M. M c C U T C H E O N , K. M A N C E R A N D I. D A R D I C K Divisions of Cytopathology and Electron Microscopy, Department of Pathology, The Toronto Hospital, Toronto General Hospital Division, Ontario, Canada Accepted for publication 30 June 1992
McCUTCHEON J. M., MANCER K. AND DARDICK 1.
(1992) Cytopathology 3,373-377
Acinic cell tumour: a metastasis in the lung diagnosed by electron microscopy of aspirated material
A case of acinic cell carcinoma, metastatic to lung is presented. Fine needle aspiration showed a low-grade adenocarcinoma. Electron microscopy of the aspirated material, however, allowed definite preoperative diagnosis of metastatic acinic cell carcinoma. The lesion was successfully resected and diagnosis confirmed on histology. Ten years previously an acinic cell carcinoma of similar histology had been excised from the left parotid region. Keywords: fine needle aspiration cytology, electron microscopy, salivary gland tumour, metastasis
INTRODUCTION Fine needle aspiration (FNA) is a most effective diagnostic technique that often avoids more invasive procedures. Ancillary diagnostic techniques such as immunocytochemistry or electron microscopy may be used on the specimens to clarify a diagnostic problem that cannot be resolved by conventional cytological preparations. We report a case in which electron microscopy of the aspirated material resulted in a confident preoperative diagnosis of metastatic acinic cell carcinoma. The diagnosis was confirmed on biopsy of the resected neoplasm. MATERIALS AND METHODS Case report A 69-year-old woman was found on chest X-ray to have a 2.5 cm mass in the right upper lobe. The lesion had been slowly increasing in size over 5 years. Ten years previously, she had a Correspondence: Dr J. M. McCutcheon, UMDS, Department of Histopathology, St Thomas’ Hospital, Lambeth Palace Road, London SEl7EH, UK.
374 J. M . McCutcheon, K. Mancer & I. Dardick
Figure 1. FNA of lung; cell block preparation. Some cytoplasmicgranularity in a well differentiated adenocarcinoma.Haematoxylin and eosin, x 400.
tumour mass resected from the left parotid region. This was shown to be mixed papillary and solid carcinoma. Electron microscopy of the tumour showed intracytoplasmic secretory material typical of the zymogen granules seen in an acinic cell carcinoma. One year later, a tumour mass was resected from subcutaneous tissue in the neck. This recurrent or metastatic tumour had a similar morphology to the original parotid lesion and an identical appearance on electron microscopy. The lung tumour was aspirated and following preoperative cytopathological and ultrastructural diagnosis, a right upper lobectomy was performed. Fluoroscopic-directed FNA of the lesion in the upper lobe of the right lung was performed. Aspirated material was immediately smeared on to glass slides, fixed in 95% alcohol and stained by the Papanicolaou method. A portion of the specimen was fixed in 2.5% gluteraldehyde and processed for electron microscopy. Further material was fixed in 50% alcohol, processed as a cell block, sectioned and then stained with haematoxylin and eosin and by the Papanicolaou method. RESULTS Cytopathology of FNA
Papanicolaou-stained smears were highly cellular, containing cohesive clusters of epithelial cells. The cells were monomorphic, with some clusters having a papillary configuration. The nuclei had a fine chromatin pattern and prominent nucleoli were seen in some cells (Figure 1).
Acinic cell carcinoma
315
Figure 2. (a) FNA of lung. Columnar cells with sparse surface microvilli and compact, densely staining zymogen-type secretory granules within the apical cytoplasm. (b) Resected (1980) parotid tumour. Tumour cells with an acinar-type arrangement and features similar to those of the FNA specimen. Uranyl acetate and lead citrate stain. (a) x 11 000, (b) x 4300.
The cytological appearances were suggestive of a low-grade adenocarcinoma. The differential diagnosis included broncholoalveolar carcinoma and low-grade papillary adenocarcinoma, possibly metastatic. The appearances did not suggest a classical acinic cell carcinoma. The tumour cells contained some weakly positive intracytoplasmic periodic acid-Schiff (PAS)-positive diastase resistant granules. Ultrastructure of FNA
Multiple fragments of well preserved tissue were present in the plastic sections cut from epon blocks. Ultrastructurally, tumour cells were cuboidal or columnar in shape, and had an orderly arrangement (Figure 2a). Adjacent cells were joined by well formed desmosomes. Many of the cells contained apical secretory granules with a homogeneous, darkly staining content; these secretory granules were of moderate and uniform size (Figure 2a). Typical
376 J . M . McCutcheon, K . Mancer & I. Dardick
Figure 3. Histology of the resected tumour with cuboidal and columnar cells forming a papillary adenocarcinoma.Haematoxylinand eosin, x 200.
mucous granules or secretory product with a lamellar configuration were not present. Both the organization of the tumour cells and their secretory product were comparable to the salivary gland tumour that had been resected 10 years before (Figure 2b). Light microscopy of resected tumour
Paraffin sections of the lung tumour showed a papillary adenocarcinoma consistent with acinic cell carcinoma (Figure 3 ) . The histology was similar to both the primary parotid gland carcinoma resected 10 years previously and the metastatic or recurrent subcutaneous lesion resected from the neck a year later. DISCUSSION Acinic cell carcinoma is a rare tumour accounting for approximately 3% of all salivary gland tumours. Metastases to cervical lymph nodes occur in 10% of cases, while metastases to lung and bone develop in approximately 15%’. The tumour has a highly variable morphology’-*. It may consist almost entirely of polygonal cells with granular, basophilic cytoplasm closely resembling normal serous acinar cells or these polygonal cells may be admixed with intercalated duct-like tumour cells; the latter are smaller than the polygonal cells and have acidophilic cytoplasm lacking the granularity of acinar-like cells. Rarely, the tumour cells are ofclear cell-type. The tumour may have a solid, trabecular, microcystic, follicular or papillary architecture. FNA cytology generally
Acinic cell carcinoma
371
results in a cellular smear3. The cells often have abundant foamy or granular cytoplasm. Typically PAS-positive diastase-resistant granules are present in tumour cells. The degree of differentiation of the acinar cells can make it difficult to categorize acinic cell carcinoma in FNA. This case highlights the use of electron microscopy of FNAs in diagnosing this rare type of metastatic adenocarcinoma in lung. A history of acinic cell carcinoma 10 years previously would not clinically preclude a diagnosis of a second primary tumour arising in lung. Radiologically the lesion could not be confidently diagnosed as either primary or metastatic. Adequate FNA material was available to establish a diagnosis of adenocarcinoma in the present case, but insufficient cytological details were present to decide whether the tumour was metastatic or represented a broncholoalveolar carcinoma. Although secretory granules were readily recognizable within the apical cytoplasm of the tumour cells, their numbers were insufficient to produce the cytoplasmic granularity required for an unequivocal diagnosis of acinic cell carcinoma. Furthermore, ultrastructurally the form and structure of the secretory granules were typical for zymogen4*’and could be distinguished from the various types of secretory cells, i.e. mucin, type I1 pneumocyte or Clara cells, that can be found in broncholoalveolar The ultrastructural characteristics of the FNA specimen led to a definite preoperative diagnosis of metastatic acinic cell carcinoma. In view of our experience with the adjunctive role of electron microscopy in FNAs7,*,we consider it prudent to save some aspirated material from deep-seated lesions for ultrastructural examination in case an unusually difficult diagnostic problem presents on light microscope examination of the specimen.
REFERENCES 1 Lewis JE, Olsen KD, Weiland LH. Acinic cell carcinoma-clinicopathologic review. Cancer 1991; 67: 172-9. 2 Ellis GL, Corio RL. Acinic cell adenocarcinoma: a clinicopathologic analysis of 294 cases. Cancer 1983; 52: 542-9. 3 Qizilbash AH, Young JEM. Salivary glands. In: Head and Neck, Guides to Ciinical Aspiration Biopsy. New York: Igaku-Shoin, 1988; 15-1 16. 4 Chaudhry AP, Cutler LS, Leifer C, Satchidanand S, Labay G, Yamane G. Histogenesis of acinic cell carcinoma of the major and minor salivary glands. Anultrastructural study. JPatholl986; 148:307-20. 5 Dardick I, George D, Jeans MTD, Wittkuhn JF, Skimming L, van Nostrand AWP. Ultrastructural
morphology and cellular differentiation in acinic cell carcinoma. Oral Surg 1987; 63:325-34. 6 Taccagni GL, Dell’Antonio G, Terreni MR, Cantaboni A. Heterogeneous subcellular morphology of lung adenocarcinoma cells;identification of different cytotypes on cytologic material. Ultrastruct Patholl990; 14 65-80. 7 Yazdi HM, Dardick I. ~mmuno~is~oche~iistry and Electron Microscopy, Guides to Clinical Aspiration Biopsy. New York: Igaku-Shoin, 1992. 8 Dardick I, Yazdi HM, Brosko C, Rippstein P, Hickey NM. A quantitative comparison of light and electron microscopic diagnoses in specimens obtained by fine needle aspiration biopsy. Uitrasiruct Pathol1991; 15: 105-26.
