Pulmonary papillary adenoma, bronchiolar adenoma, peripheral papillary adenoma of type II pneumocytes

Some authorities consider this tumour a variant of sclerosing haemangioma.

Epidemiology

This is a rare tumour: less than 20 cases have been reported in the literature. A case of multiple papillomas has been reported in a boy with von Recklinghausen's disease⁷.

Radiology

The patients are usually asymptomatic with an incidental well defined peripheral pulmonary nodule or "coin lesion"^5,6.

Macroscopic appearances

The tumour is well defined. Statements as to whether they involve airways vary^0,5,9.

Histopathology

These tumours are usually well-demarcated and non-infiltrating. Cases with infiltrative margins have been reported, but the significance for their behaviour is uncertain². The architecture is papillary, mixed with more solid areas. The cells resemble pneumocytes/Clara cells, with cuboidal to columnar cells showing eosinophilic cytoplasm. There is an absence of nuclear atypia and necrosis⁶. Occasional nuclear eosinophilic inclusions may be seen. Oncocytic cases are reported⁴.

Immunohistochemistry

	surface cells	stromal cells
Cytokeratins	positive8, 2/22
MNF116	1/11	0/11
EMA	1/11, 1/17	0/11
CEA	positive8, 1/18
TTF-1	positive8, 1/11, 2/22	0/11
surfactant protein	positive8, 2/22, 1/14, 0/36, 1/17, 1/18, 1/110
Neuroendocrine markers	negative8
Clara cell specific protein	1/16

Ultrastructure

Cells have microvilli^2,3, sparse cell junctions³, cytoplasmic dense granules^3,8 and whorled lamellar membrane inclusions^2,3,4,8,9,10, features of type II pneumocytes/Clara cells.

Differential diagnosis

• Sclerosing haemangioma usually shows a mixed pattern of with solid, angiomatoid and papillary areas. Both surface and stromal cells are positive for TTF-1.

• Alveolar adenoma: lacks a papillary pattern.

• Papillary adenocarcinoma: there is cytological atypia

• Papillary carcinoid: granular cytoplasm, finely granular chromatin, positive for neuroendocrine markers

Prognosis

These tumours have never been reported to metastasis⁹.

References

⁰Tumours of the Lung, Pleura, Thymus and Heart. WHO Classification of Tumours. IARC Press 2004.

¹Sheppard, M. N., Burke L. et al. (2003). "TTF-1 is useful in the diagnosis of pulmonary papillary adenoma." Histopathology 43(4): 404-5.

²Dessy E, Braidotti P, Del Curto B, et al. Peripheral papillary tumor of type-II pneumocytes: a rare neoplasm of undetermined malignant potential. Virchows Arch 2000; 436:289-95

³Fantone JC, Geisinger KR,Appelman HD Papillary adenoma of the lung with lamellar and electron dense granules. An ultrastructural study. Cancer 1982; 50:2839-44

⁴Fine G,Chang CH. Adenoma of type 2 pneumocytes with oncocytic features. Arch Pathol Lab Med 1991; 115:797-801

⁵Fukuda T, Ohnishi Y, Kanai I, et al. Papillary adenoma of the lung. Histological and ultrastructural findings in two cases. Acta Pathol Jpn 1992; 42:56-61

⁶Hegg CA, Flint A,Singh G Papillary adenoma of the lung. Am J Clin Pathol 1992; 97:393-7

⁷Kurotaki H, Kamata Y, Kimura M, et al. Multiple papillary adenomas of type II pneumocytes found in a 13-year-old boy with von Recklinghausen's disease. Virchows Arch A Pathol Anat Histopathol 1993; 423:319-22

⁸Mori M, Chiba R, Tezuka F, et al. Papillary adenoma of type II pneumocytes might have malignant potential. Virchows Arch 1996; 428:195-200

⁹Noguchi M, Kodama T, Shimosato Y, et al. Papillary adenoma of type 2 pneumocytes. Am J Surg Pathol 1986; 10:134-9

¹⁰Yamamoto T, Horiguchi H, Shibagaki T, et al. Encapsulated type II pneumocyte adenoma: a case report and review of the literature. Respiration 1993; 60:373-7

This page last revised 31.3.2005.

©SMUHT/PW Bishop