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

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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 inappropriate.

benign

is 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.

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.

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.

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%.

CYTOKERATIN POOL

S-100 PROTEIN

SMOOTH MUSCLE ACTIN

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.

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 and metastases.

the primary tumour

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