Benign lesions

Benign clear cell tumor ('sugar' tumor)

It is a rare tumor, occurring in any age as an asymptomatic peripheral nodule. Because of their immunohistochemical and ultrastructural features, they have been supposed to origin from pericytes; anyway, their origin is a matter of discussion. They consist of polygonal cells with clear, glycogen-rich cytoplasm.

Cytologic diagnostic features

  • Clusters of polygonal and spindle-shaped cells
  • Vacuolated or granular cytoplasm
  • PAS-positive cytoplasm

Differential diagnosis

  • Non-small cell carcinoma with clear cell change
  • Carcinoid tumor
  • Metastatic renal cell carcinoma

Immunocytochemistry is helpful: most sugar tumors are positive for HMB-45, CD34 and S-100 and negative for cytokeratins and CEA.

Pulmonary hamartoma

It presents as an incidental nodule on radiographs, particularly in elderly men. A hamartoma is a neoplasm in an organ that is composed of tissue elements normally found at that site, but growing in a haphazard mass.

Transthoracic FNA is very sensitive and specific in diagnosing this lesion. A mixture of mesenchymal (mainly fibromyxoid and cartilaginous material) and epithelial elements is seen in FNA material. Bland spindle cells in a fibromyxoid stroma and mature cartilage, with chondrocyte in lacunae, are observed; epithelial glandular cells and adipocytes are often present.

Pulmonary hamartoma.

Note the biphasic morphology with a fragment of benign-appearing epithelium and fibromyxoid stromal tissue.

Pulmonary hamartoma.

Biphasic appearance of the tumor with predominance of chondromyxoid stromal tissueand some epithelial cells seen singly and in loose clusters.

Pulmonary hamartoma. A dimorphic population of benign fragmented epithelium and cellular fibroblastic stromal tissue.

Pulmonary hamartoma.

Epithelial component of the tumor appearing as monolayered fragments of monotonous benign tissue.

FNA hamartoma
Histology hamartoma
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