Introduction

The limitation of cytology is well known. However, the cause of this limitation is sometimes not discussed enough. The purpose of this lecture is to introduce major causes that mislead physicians about cytological diagnosis, and some solutions. This lecture will be demonstrated by related cases with macroscopic and microscopic photographs. Issues of tissue sampling techniques will be talked in the other sessions of this conference.

Major causes that disturb cytological diagnosis:

 Similarity of cell morphology: Granulation tissue vs. Fusiform cell tumors

 Poor cellularity: Fusiform cell tumors, e.g., fibrosarcoma, and osteosarcoma

 Lymphoma vs. lymphocytic hyperplasia

 Poor malignant features in histologically malignant tumors: Mammary carcinoma in cats

Solutions that we provide after the first cytological evaluation:

 FNA after stamp smear: Epitheliotropic lymphoma at tumor stage, and nasal tumors

 Core biopsy after FNA: Granulation tissue vs. fusiform cell tumors

 Importance of core biopsy for comparative diagnosis between epithelial tumors and mesenchymal tumors: trichoblastoma vs. hemangiopericytoma

 Limit of tru-cut biopsy: Lymphoma which requires a cytological analysis rather than histological architecture evaluated by a thinner tissue that can be easily destroyed.

Namba Veterinary Pathological Laboratory, Setagaya Kamiuma 4-2-9-1209, Tokyo, 154-0011, Japan, Email: BZG14356@nifty.com, Web page: http://homepage2.nifty.com/p-tuat-vet/namba/home.html