Carcinoid tumor is very rare primary tumor in the thymus, first described by Rosai
and Levine in 1972. Before Rosai and Levine, it was diagnosed as epithelial tumor of the
thymus or bronchial adenoma-like tumor of the mediastinum.
Recently the authors experienced a case of primary thymic carcinoid tumor diagnosed
by histopathologic, histochemical, and electronmicroscopical study.
A 54 years old policeman was admitted for surgical intervension, because of a chest
mass that was detected in routine chest x-ray. He had been well being until the mass
was found.
On admission. Physical examination was all within normal limit. Laboratory findings
were within normal limit, except the fasting blood sugar was 141 ㎎/dl, and postprandial
sugar, 225 ㎎/dl.
An exploratory thoracotomy was performed, and an anterior mediastinal mass was
easily removed. During the operation, any metastatic mass or other abnormalities were
not observed.
The mass was a well encapsulated multilobulated mass, measured 12.0 M 6.5 N 7.0
cm and weighing 280 gm. On cut section, it revealed homogeneous tan gray lobulated
cut surface with firm consistency. Any necrotic and hemorrhagic areas were not found
grossly.
Microscopically this tumor consisted of diffuse pattern of monomorphic cells, or
rosette-forming area, and ribbon-like arranged areas. Argyrophil stain revealed scattered
argyrophil cells, and argentaffin stain was negative.
Electronmicroscopic study revealed some membrane-bounded electron dense granule
which were measured 50-150nm, in the cytoplasm. That were consistent with
neurosecretory granules, found in the carcinoid tumor of the foregut.
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