Micropapillary carcinoma of the colon

Definition

A tumour wholly are partly composed of small clusters of tumour cells within stromal spaces resembling lymphatic channels, equivalent to the micropapillary tumours of breast, lung, urinary tract and salivary gland.

Histopathology

The tumour forms small pseudopapillae devoid of fibrovascular cores. D2-40 demonstrates that not all the spaces around the papillae are lined by lymphoendothelium.

Immunohistochemistry

The cells show reverse polarity with the apical membrane facing outwards, resulting in immunoreactivity for MUC-1 and EMA on the outer membrane.

	EMA	2/3 (staining of the outer membrane)1
	MUC-1	3/3 (staining of the outer membrane)1
	E-cadherin	3/31
	CK7	0/31
	CK20	3/31

Differential diagnosis

• Ordinary colonic carcinoma with extensive lymphatic invasion: the tumour foci are surrounded by lymphoendothelium. The tumour does not show the staining of the outer membrane by MUC-1 and EMA.

• Metastasis from breast, lung, ovary, salivary gland: CK7+/CK20-. Metastases from the urinary tract are CK7+/CK20+/

Prognosis

Too few cases have been reported to assess prognosis.

References

¹ Sakamoto K, Watanabe M, De La Cruz C, et al. Primary invasive micropapillary carcinoma of the colon. Histopathology 2005; 47:479-84

This page last revised 27.11.2005.

©SMUHT/PW Bishop