Cosmic Signs in Radiology: A Pictorial Review

Pattern recognition remains a cornerstone of radiologic interpretation, as it facilitates a confident and comprehensive differential diagnosis. Certain pathologies present with specific and highly recognizable patterns on imaging modalities. These patterns can resemble familiar real-life phenomena, including cosmic bodies that surround us. We present in this article a compilation of radiologic signs across various modalities that take inspiration from cosmic phenomena. For each sign, we summarize its defining imaging appearance, typical clinical context, and common pitfalls; where available, we note diagnostic performance (e.g., sensitivity/specificity) to guide appropriate weighting in practice. By coupling memorable imagery with succinct clinical guidance, this pictorial review aims to support a faster, more accurate pattern recognition that is applicable in both low-resource and tertiary care settings, while recognizing that these signs function as educational aids rather than validated diagnostic tests. In familiarizing themselves with these classic signs, training radiologists can benefit from an engaging and memorable way of recognizing various pathological conditions.