Novel, diagnostic, cytomorphometric profile of canine, classical haemangiopericytoma: including nuclear criteria of malignancy

Abstract

Diagnosis of classical, canine haemangiopericytoma (HPCA) may be equivocal. This study aims to define a unique, diagnostic, cytomorphometric profile of HPCA. This is a retrospective analysis of 61 HPCA cytological reports and specimens. Ages were 9.5 ± 2.6 years, and 53% were male. Odds ratio for HPCA was highest in Siberian huskies (8%), Staffordshire bull terriers (5%), boxers (4%), border collies (4%), terriers (3%), and English springer spaniels (2%). Fifty percent HPCA affected forelegs, 19% hindlegs, and 20% trunks. Cellularity was moderate-to-high. 819 ± 612 cells were examined per case. One hundred percent cases had good cellularity and peripheralized multinucleation in 6.2 ± 3.5% cells as “insect-heads” and 1.7 ± 1.4% cells as “crowns” (for 95% cases) with 4 ± 1 peripheralized nuclei. Of cases, ≥ 92% had micronuclei with diameters of 1.6 ± 0.3 µm in 1.2 ± 0.9% cells. Veil-like cytoplasm, nuclear moulding, extracellular matrix, whirling pattern, and capillaries were present in 95%, 85%, 82%, 57%, and 48% cases, respectively. Anisokaryosis was 1.9 ± 0.3-fold; anisonucleoliosis is 3.7 ± 1.1-fold. Novel, HPCA nuclear features are micronuclei, nuclear moulding, increased size, and size variation of nuclei and nucleoli. Our diagnostic, cytological profile consists of good cellularity, frequent insect-head cells, and at least 3 of the following: (i) crown cells, (ii) micronuclei, (iii) cytoplasmic distinction—whirling or veil-like or microvacuolation, (iv) extracellular distinction—capillaries or extracellular matrix, and (v) a second, malignant nuclear feature—2.5-fold anisonucleoliosis, nuclear moulding, or nucleoli ≥ 0.5 RBC diameter. Implementation of this cytological profile over 2 years since the above analysis gave fourfold increase in frequency of diagnosis of HPCA. A novel profile with novel features fits all HPCA cases and quadrupled detection rate.