Cross-talk between tumour and immune cells, including macrophages, is complex, dynamic and contributes to tumour heterogeneity. In this paper, we introduce a hybrid agent-based model (ABM) to investigate how tumour-macrophage dynamics evolve over time and how they influence spatial patterns of tumour growth. Macrophage phenotype is determined by microenvironmental cues and governs the extent to which macrophages are pro- or anti-tumour, i.e., whether they infiltrate and attack tumour cells, or promote metastasis by guiding tumour cell migration towards blood vessels.We perform extensive ABM simulations to investigate how changes in macrophage sensitivity to microenvironmental cues – specifically, cytokines produced by tumour cells and perivascular fibroblasts – alters their spatial and phenotypic distributions and the tumour’s growth dynamics. We identify outcomes that include: compact tumour growth, tumour elimination, and diffuse patterns of invasion, characterised by clustering of tumour cells and macrophages around blood vessels.We compare the ability of different statistics to characterise the diverse spatial patterns that the ABM generates. These include the weighted pair correlation function (wPCF), a new statistic that quantifies the spatial distributions of cells labelled with a continuous value (e.g., macrophage phenotype). We assess the ability of each statistic to discriminate between the various spatial patterns that the ABM exhibits.By combining statistical analysis with ABM simulations, we show how mechanistic models can be used to generate synthetic data for validation of novel statistics (here, the wPCF) and to assess the extent to which specific statistical descriptions can distinguish different spatial patterns and model behaviours. Such statistics can then be applied to biological imaging data, such as multiplexed medical images, with increased confidence in the interpretation of the results. We show that the wPCF accurately describes differences in macrophage localisation between images, and posit that it would be a valuable tool for analysing multiplexed imaging data.Author summaryMacrophage phenotype is regulated by complex microenvironmental cues. It affects their spatial position and behaviour. In solid tumours, the spatial distribution of macrophages can vary significantly, and correlate with patient prognosis.In this paper, we use an agent-based model (ABM) to investigate how changes in sensitivity to tumour-induced microenvironmental cues affect macrophage phenotype and, in turn, how such phenotypic heterogeneity affects tumour composition and morphology. We illustrate the wide range of tumour outcomes that can arise from changing macrophage sensitivity to microenvironmental cues.We apply a variety of statistics to simulation outputs to characterise the range of observed spatial patterns. Different statistics identify different aspects of these patterns, with the most descriptive characterisations obtained from spatial statistics, such as the weighted pair correlation function (wPCF), that account for both phenotype and cell localisation.More generally, this paper illustrates how ABMs can be used to generate synthetic data which mimics data that can be extracted from different imaging modalities. This synthetic data can be used to test new statistics, like the wPCF, and validate their use for future application to multiplex histological imaging.