Probes for INS

Abstract

INTRODUCTION:

Localized- and diffuse-type tenosynovial giant cell tumours (TGCT) are regarded different clinical and radiological TGCT-types. However, genetically and histopathologically they seem indistinguishable. We aimed to correlate CSF1-expression and CSF1-rearrangement with the biological behaviour of different TGCT-types with clinical outcome (recurrence).

METHODS:

Along a continuum of extremes, therapy naïve knee TGCT patients with >3 year follow-up, mean age 43(range 6-71)years and 56% female were selected. Nine localized-(two recurrences), 16 diffuse-type(nine recurrences) and four synovitis as control were included. Rearrangement of the CSF1-locus was evaluated with split-apart Fluorescence In Situ Hybridization (FISH) probes. Regions were selected to score after identifying CSF1-expressing regions, using mRNA ISH with the help of digital correlative microscopy. CSF1-rearrangement was considered positive in samples containing >2 split signals/100 nuclei.

RESULTS:

Irrespective of TGCT-subtype, all cases showed CSF1-expression and in 76% CSF1-rearrangement was detected. Quantification of CSF1-expressing cells was not informative, due to the extensive intra tumour heterogeneity. Of the four synovitis cases, two also showed CSF1-expression, without CSF1-rearrangement. No correlation between CSF1-expression or rearrangement with clinical subtype and local recurrence was detected. Both localized- and diffuse-TGCT cases showed a scattered distribution in the tissue of CSF1-expressing cells.

CONCLUSION:

In diagnosing TGCT, CSF1 mRNA-ISH in combination with CSF1 split-apart FISH; using digital correlative microscopy, is an auxiliary diagnostic tool to identify rarely occurring neoplastic cells. This combined approach allowed us to detect CSF1-rearrangement in 76% of the TGCT-cases. Neither CSF1-expression nor presence of CSF1-rearrangement could be associated with the difference in biological behaviour of TGCT. 

Regardless of host, pathogenic mycobacteria of the Mycobacterium tuberculosiscomplex such as Mycobacterium bovis, induce a characteristic lesion known as agranuloma, tubercle or tuberculoid granuloma. Granulomas represent a distinct host response to chronic antigenic stimuli, such as foreign bodies, certain bacterial components, or persistent pathogens such as M. bovis. Granulomas are composed of specific cell types including epithelioid macrophages, lymphocytes and a morphologically distinctive cell type, the multinucleated giant cell. Multinucleated giant cells are formed by the fusion of multiple macrophages; however, their function remains unclear. In humans, giant cells in tuberculous granulomas have been shown to express various cytokines, chemokines and enzymes important to the formation and maintenance of the granuloma. The objective of this study was to quantitatively assess multinucleated giant cell cytokine expression in bovine tuberculoid granulomas; focusing on cytokines of suspected relevance to bovine tuberculosis. Using calves experimentally infected with M. bovis, in situ cytokine expression was quantitatively assessed using RNAScope^® for the following cytokines TNF-α, IFN-γ, TGF-β, IL-17A and IL-10. Multinucleated giant cells in bovine tuberculoid granulomas expressed all examined cytokines to varying degrees, with differential expression of TGF-β, IL-17A and IL-10 in giant cells from early versus late stage granulomas. There was a modest, positive correlation between the level of cytokine expression and cell size or number of nuclei. These results suggest that multinucleated giant cells are active participants within bovine tuberculoid granulomas, contributing to the cytokine milieu necessary to form and maintain granulomas.