Carcinoma of the lung with rhabdoid features

Definition

A lung tumour of which at least 10% is of rhabdoid appearance, the cells having large globular cytoplasmic inclusions. Cases with less than 10% rhabdoid cells have been designated as "lung carcinoma with a small number of rhabdoid cells"3. There is no evidence of true rhabdomyoblastic differentiation. It is considered a variant of large cell carcinoma.

Epidemiology

These are very rare lung tumours, occurring in the middle aged to elderly with a male predilection.

Macroscopic appearances

The tumours are poorly circumscribed with foci of haemorrhage and necrosis. There is often pleural infiltration and nodal metastases.

Histopathology

The tumours are poorly differentiated, composed of cells contain a large cytoplasmic inclusion. The nucleus is eccentric with a prominent nucleolus.

The other component may be large cell, adenocarcinoma1,2, large cell neuroendocrine or sarcomatoid4.

Immunohistochemistry

	rhabdoid component	glandular component
TTF-1	0/114, 0/15	5/94
EMA	5/6(positivity in the inclusions)1, 6/143, 1/15	2/21, 9/143,
Cytokeratin	3/6(positivity in the inclusions)1	2/21
AE1/AE3	12/143, 9/11(positivity in the inclusions)4	14/143, 8/94
Cam5.2	2/6(positivity in the inclusions)1 , 1/15	2/21
CK7	4/10(positivity in the inclusions)4	5/84
CK20	0/104	0/84
Vimentin	6/61, 14/143, 11/11(positivity in the inclusions)4, 1/15	0/21 , 7/94
GFAP	1/6(positivity in the inclusions)1, 0/143	0/21
Chromogranin	3/6(positivity in the inclusions)1, 2/143	0/21
Synaptophysin	3/6(positivity outwith the inclusions)1, 1/143	0/21, 4/143
Neurofilament	2/6(positivity in the inclusions)1, 1/143	0/21
CD57	1/6(positivity in the inclusions)1, 0/143	0/21
CD117	0/143
NSE	5/6(positivity in the inclusions)1, 5/143	0/21
Factor VIII	0/61	0/21
CD34	1/6(positivity outwith the inclusions)1, 0/143	0/21
Muscle-specific actin	0/61, 0/143	0/21
Desmin	0/61, 0/143	0/21
S-100	0/61	0/21
HMB45	0/61, 0/143	0/21
Myoglobin	1/61, 0/143	0/2
light chains	0/11

Ultrastructure

There are paranuclear aggregates of intermediate filaments, dense core granules and intercellular attachments3 .

Differential diagnosis

Metastatic malignant rhabdoid tumour
Mucinous signet ring cell carcinoma, primary or metastatic
Malignant melanoma: positive for S-100 and HMB45
Rhabdomyosarcoma
Epithelioid angiosarcoma
Leiomyosarcoma
Plasmacytoma

Prognosis

These tumours are aggressive2,4,5.

References

1 Cavazza A, Colby TV, Tsokos M, et al. Lung tumors with a rhabdoid phenotype. Am J Clin Pathol 1996; 105:182-8

2 Chetty R, Bhana B, Batitang S, et al. Lung carcinomas composed of rhabdoid cells. Eur J Surg Oncol 1997; 23:432-4

3 Shimazaki H, Aida S, Sato M, et al. Lung carcinoma with rhabdoid cells: a clinicopathological study and survival analysis of 14 cases. Histopathology 2001; 38:425-34.