PULMONARY METASTASIS FROM SUBMANDIBULAR BENIGN PLEOMORPHIC ADENOMA: REPORT OF A CASE

1. -- Istituto di Anatomia ed Istologia Patologica -- PERUGIA 2009 PULMONARY METASTASIS FROM SUBMANDIBULAR BENIGN PLEOMORPHIC ADENOMA: REPORT OF A CASE A. Pireddu, M. Spinelli, M. Giansanti, A. Sidoni, A. Cavaliere. Istituto di Anatomia e Istologia Patologica Università degli Studi, Perugia

2. -- Istituto di Anatomia ed Istologia Patologica -- PERUGIA 2009 INTRODUCTION • Metastasizing pleomorphic adenoma (MPA) is an extremely rare metastasis of histologically benign tumour. Nevertheless, the aggressive outcome of some cases indicates that the adjective benign is inappropriate. • Typically, the metastasis and the primary salivary gland tumour are histologically identical to the benign tumour. • We describe a case of pulmonary metastasis from submandibular pleomorphic adenoma.

3. -- Istituto di Anatomia ed Istologia Patologica -- PERUGIA 2009 CASE HISTORY A 51-year-old woman showed a lung nodule and two pancreas lesions. She had past medical history of pleomorphic adenoma of the submandibular gland (7 years before) locally recurred two years after diagnosis. A computed tomography-guided needle biopsy of the pulmonary nodule was performed.

4. -- Istituto di Anatomia ed Istologia Patologica -- PERUGIA 2009 PATHOLOGICAL FINDINGS The histologic exam of formalin-fixed and paraffin embedded tissue evidenced a neoplasm made up of small cells with no atipia in a variable amount of fibromyxoid tissue.

5. -- Istituto di Anatomia ed Istologia Patologica -- PERUGIA 2009 IMMUNOHISTOCHEMICAL FEATURES • The cells were immunoreactive for cytokeratin pool, smooth muscle actin and S-100 protein. • They were negative for chromogranin, synaptophysin and TTF-1. • The proliferative index Ki-67 (MIB-1) was 3%.

6. -- Istituto di Anatomia ed Istologia Patologica -- PERUGIA 2009 CYTOKERATIN POOL

7. -- Istituto di Anatomia ed Istologia Patologica -- PERUGIA 2009 S-100 PROTEIN

8. -- Istituto di Anatomia ed Istologia Patologica -- PERUGIA 2009 SMOOTH MUSCLE ACTIN

9. -- Istituto di Anatomia ed Istologia Patologica -- PERUGIA 2009 DISCUSSION 1 • MPA was first described in 1942. • The mechanism underlying its metastatic behaviour is still not certain. • The majority of the tumours origins from the parotid gland, while there are a few reports of metastasis from the submandibular gland.

10. -- Istituto di Anatomia ed Istologia Patologica -- PERUGIA 2009 DISCUSSION 2 • Bone, lung and lymph nodes are the most common sites of metastatic disease, but kidney, liver, CNS, retroperitoneum and skin can also be involved. • As in our case, there is often a long interval between diagnosis of the primary tumour and metastases.

11. -- Istituto di Anatomia ed Istologia Patologica -- PERUGIA 2009 BIBLIOGRAPHY Czader M, Eberhart CG, Bhatti N, Cummings C, Westra WH. Metastasizing mixed tumor of the parotid: inizial presentation as a solitary kidney tumor and ultimate carcinomatous transformation at the primary site. Am J Surg Pathol, 24:1159-1164, 2000 Raja V, China C, Masaki KH, Nakano G. Unusual presentations of uncommon tumors: case 1. Benign metastasizing pleomorphic adenoma. J Clin Oncology, 20:2400-2403, 2002 Sit K Y, Chui W H, Wang E, Chiu SW. Multiple pulmonary metastases from benign pleomorphic adenoma. Asian Cardiovasc Thorac Ann, 16:62-4, 2008