Pulmonary acinic cell carcinoma (Fechner tumour) with carcinoid component. A case report

Among bronchial tumours connected with bronchial glands we distinguish mucoepidermoid carcinoma, adenoid cystic carcinoma, epithelial-myoepithelial carcinoma, pleomorphic adenoma and acinic cell carcinoma. The last two are extremely rare. The first case of acinic cell carcinoma was described by Fechner in the year 1972 [1]. Since then there have been only a few new cases described. Moran et al. [2] have published the largest group of such cases. Tumours formed from two components, acinic cells and neuroendocrine carcinoid cells, are even more rare. In the recent English literature there are two reports concerning mixed carcinoid and acinic cell tumours from Japan and Italy [3, 4]. The rarity of this kind of tumours may lead to incorrect diagnosis when pathologists first come across such cases. Recently we have had an opportunity to diagnose one tumour of this type.

Material and methods

A 63-year-old man was admitted to the hospital in January 2009 because of a tumour in his right lung in the vicinity of the mediastinum visible on chest X-ray (Fig. 1). There were no other signs of the disease. During surgery the tumour was removed together with part of the upper and middle right lobes. Intraoperative pathological study suggested a neoplastic tumour – probably liposarcoma. The tumour was 52 × 23 × 18 mm in diameter. Material was fixed in formalin and embedded in paraffin blocks No. 190019. Frozen material was used for Sudan III staining. Slides and paraffin blocks were sent for consultation to the Chair of Pathomorphology, Jagiellonian University Medical College. The slides from paraffin blocks were used for HE staining, PAS with/without previous diastase digestion, Gomori silver staining as well as immunohistochemical staining against: cytokeratin AE1/AE3, cytokeratin 5/6, chromogranin A, synaptophysin, S-100, EMA, 1-antichymotrypsin, smooth muscle actin, CD10, Ki67, CD68, CD99, HMB45, lysozyme, calretinin, and NSE. Additionally, formalin-fixed, paraffin embedded tissue slides were used for FISH analysis with commercially available SYT Dual Color Break Apart probes (Vysis LSI SS18 LOT 420 582).

Results

Histological analysis revealed a neoplastic tumour with solid growth pattern, composed predominantly of a sheet of cells with clear, empty cytoplasm and distinct borders (Fig. 2 and 3). Both PAS and PAS treated with diastase staining were distinctly positive (Fig. 4) but Sudan III was negative in their cytoplasm. Nuclei of the cells were eccentrically located, round or oval, and only a few cells presented visible nucleoli. Some cells looked like signet ring cells. No mitotic figures were seen, but 20 to 30% of nuclei were positively stained with Ki67 antibody. At the border, the tumour infiltrated the walls of smaller bronchi. In the central part of the tumour, there were many thin-walled, mostly capillary blood vessels. They were focally surrounded by lymphocytic infiltration. Clear cells were stained negatively for EMA and cytokeratins; a few of them were dyed immunohistochemically for lysozyme.

On the border of the tumour and less commonly in central parts there were dispersed tubular and slit-like structures lined by cuboidal cells with a small amount of cytoplasm; all these cells were stained with antibodies against pancytokeratin (Fig. 5), EMA as well as for chromogranin (Fig. 6) and synaptophysin. Antigens HMB45, CD68, CD10, S-100, cytokeratin 6/8 and calretinin were negative, smooth muscle actin positive only in the wall of small blood vessels. CD99 was weakly positive in parts epithelioid cells lined tubular structures.

Since the surgery in January 2009 the patient has remained alive with no signs of the disease.

Discussion

The first step in differential diagnosis of this tumour is clinical investigation and exclusion of metastases of clear cell carcinoma from the kidney and adenocarcinoma from salivary gland.

Primary bronchial squamous cell carcinoma and adenocarcinoma with clear cells have many typical features which enable the differentiation.

Other possible diagnoses are sugar tumour – clear cell tumour (pecoma) and clear cell carcinoid. Sugar tumour, also known as clear cell tumour, is characterized by a positive reaction with HMB45 and S-100. These antigens were negative in the presented tumour. Clear cell carcinoid is a very rare type of carcinoid tumours and description of the first case in lung was published in 1998 by Gaffey et al. [5]. All cells in clear cell carcinoid are stained positively with antibodies against chromogranin, synaptophysin and neuron-specific enolase. These cells are negative with fat staining and PAS staining. Also electron microscopy investigation shows characteristic neurosecretory-type granules in the cytoplasm. Our tumour presents partially neuroendocrine differentiation but clear cells do not look like typical carcinoid cells because of negativity for chromogranin and synaptophysin and the positive PAS staining. Rodriguez et al. [4] reinforced the hypothesis that both neuroendocrine and acinic cells derive from a common stem cell. It is possible that some carcinoids and acinic cell carcinomas located in lungs are mixed tumours but were not examined as such.

Another problem is differentiation of this tumour with very rare biphasic synovial sarcoma with myxoid stroma [6]. Negative investigation both for specific breaks of chromosome 18q11 and calretinin expression makes it possible to reject the diagnosis of synovial sarcoma.

Lack of cytokeratin and EMA staining in clear cells is observed in many cases of clear cell carcinoma of salivary glands [7].

Prognosis for a patient with acinic cell carcinoma after surgery is rather good. A few cases with local recurrences and metastases to the lymph nodes have been described so far [8, 9].

References

 1. Fechner RE, Bentinck BR, Askew JB. Acinic cell tumor of the lung. Cancer 1972; 29: 501-508.  

2. Moran CA, Suster S, Koss MN. Acinic cell carcinoma of the lung (“Fechner tumor”). A clinicopathologic, immunohistochemical, and ultrastructural study of five cases. Am J Surg Pathol 1992; 16: 1039-1050.  

3. Miura K, Morinaga S, Horiushi M, et al. Bronchial carcinoid tumor mimicking acinic cell tumor. Acta Pathol Jpn 1988; 38: 523-530.  

4. Rodriguez J, Diment J, Lombardi L, et al. Combined typical carcinoid and acinic cell tumor of the lung: a heretofore unreported occurrence. Hum Pathology 2003; 34: 1061-1065.  

5. Gaffey MJ, Mills SE, Frierson HF, et al. Pulmonary clear cell carcinoid tumor. Another entity in the differential diagnosis of pulmonary clear cell neoplasia. Am J Surg Pathol 1998; 22: 1020-1025.  

6. Laga AC, Allen TG, Cagle PhT. Synovial sarcoma. In: Color atlas and text of pulmonary pathology. Cagle PhT (ed.). Walters Wolters Kluver, Lippincott Williams & Wilkins, Philadelphia 2008; 152-153.  

7. Ellis GL, Auclair PL. Acinic cell carcinoma. In: Surgical pathology of the salivary glands. Ellis GL, Auclair PL, Gnepp DR (eds.). Vol. 25 in the series: Major problems in pathology. Saunders, Philadelphia 1991; 299-317.  

8. Chuah KL, YapWM, Koong HN. Recurence of pulmonary acinic cell carcinoma. Arch Pathol Lab Med 2006; 130: 932-933.  

9. Lee HY, Mancer K, Koong HN. Primary acinic cell carcinoma of the lung with lymph node metastasis. Arch Pathol Lab Med 2003; 127: e216-319.

Address for correspondence

Bolesław Papla , MD, PhD

Jagiellonian University Medical College

ul. Grzegórzecka 16

31-531 Kraków

e-mail: bolekpapla@gmail.com