Small cell carcinoma of the breast
Epidemiology
Primary small cell carcinoma of the breast is exceedingly rare. The
reported cases occurred in middle aged to elderly women6.
Histology
The tumour has infiltration margins. The cells resemble those of
small cell carcinoma of the lung or other sites, with small nuclei,
nuclear moulding, scant cytoplasm, finely granular chromatin and
inconspicuous nucleoli. The cells may form solid, trabecular or
alveolar patterns. Crush artefact and an Azzopardi effect may occur6.
Small cell carcinoma may be combined with conventional intraduct,
invasive ductal or lobular carcinoma.
Immunohistochemistry
|
|
|
AE1/AE3 |
1/21, 10/10
(all cases strongly positive)6 |
|
Cam5.2 |
1/21, 8/106 |
|
CK7 |
8/106 |
|
CK19 |
7/96 |
|
CK20 |
0/106 |
|
Chromogranin |
1/21, 4/106 |
|
Synaptophysin |
1/21, 5/106 |
|
NSE |
10/10 (all
cases strongly positive)6 |
|
CD56 |
7/96 |
|
CD57 |
3/96 |
|
Calcitonin |
3/106 |
|
Gastrin-releasing peptide |
2/96 |
|
Neurofilament |
0/96 |
|
Somatostatin |
0/96 |
|
Serotonin |
0/96 |
|
CD99 |
1/2 (focal)1 |
|
Oestrogen receptor |
0/21, 6/106 |
|
Progesterone receptor |
0/21, 5/106 |
|
bcl-2 |
10/106 |
|
TTF-1 |
1/12, 1/23, 2/104, 1/15, 1/26,
1/3
(described as high-grade neuroendocrine tumours)5 |
|
E-cadherin |
11/114 |
|
Vimentin |
4/96 |
|
Her2/neu |
0/106 |
|
Ki-67 index |
76%1, 95%1 |
|
p53 |
negative1, 6/96 |
|
|
Differential diagnosis
Prognosis
In the largest series, although 2 of 9 patients developed metastases,
all 9 were alive with follow up of 3 to 35 months6.
References
1Hoang,
M. P., Maitra, A., Gazdar, A. F., Albores-Saavedra, J. Primary
mammary small-cell carcinoma: a molecular analysis of 2 cases. Human
Pathol 2001;32:753-757.
2Kaufmann
O & Dietel M. Expression of thyroid transcription factor-1 in
pulmonary and extrapulmonary small cell carcinomas and other
neuroendocrine carcinomas of various primary sites. Histopathology
2000; 36: 415-420
3Cheuk
W et al. Immunostaining for thyroid transcription factor-1 and
cytokeratin 20 aids in the distinction of small cell carcinoma from
Merkel cell carcinoma, but not pulmonary from extrapulmonary small
cell carcinoma. Arch Pathol Lab Med 2001;125:228-231. (supplemented
by personal communication).
4 Shin
SJ, DeLellis RA,Rosen PP. Small cell carcinoma of the
breast--additional immunohistochemical studies. Am J Surg Pathol
2001; 25:831-2
5 TTF-1
Barbareschi, M., C. Roldo, et al. (2004). "CDX-2 homeobox gene
product expression in neuroendocrine tumors: its role as a marker of
intestinal neuroendocrine tumors." Am J Surg Pathol 28(9): 1169-76.
6 Shin
SJ, DeLellis RA, Ying L, et al. Small cell carcinoma of the breast:
a clinicopathologic and immunohistochemical study of nine patients.
Am J Surg Pathol 2000; 24:1231-8
©SMUHT/PW Bishop