Descriptions of medical findings are typically expressed in a sober, sometimes cold language. Accuracy and efficiency are their purpose, set phrases heavy with meaning and countless abbreviations their means. Occasionally, they draw on pragmatic comparisons, e.g. when the size of lesions is described by a variety of fruits. However, medical language sometimes ventures off, finds playful terms and becomes nearly poetical when it tells about Bochdalek’s flower basket, diagnoses a nutmeg liver or draws Heubner’s star map. These and a multitude of other visual comparisons are often more poignant than the analysis of the infinitely complex diversity of forms of the human body and its diseases could ever be. These metaphorical shortcuts express their meaning more effectively, draw a more impressive picture and are also much easier to keep in mind.
Considering such expressions, not those that designate simple forms and shapes are worth mentioning: The rhomboid major muscle would not deserve further attention if its failure would not lead to a protrusion of the scapula, a typical symptom referred to as an angel’s wing. These comparisons with more sophisticated images – the raspberry tongue, the horseshoe kidney, the butterfly fracture and the honeycomb lung – are those that emphasise the visual nature of medical diagnostics. One usually finds them in such specialties that cultivate vision to a high degree: in anatomy and macro- as well as microscopic pathology, in dermatology, ophthalmology, and also in radiology. They often dominate the diagnostic classification of a clinical picture, appear side by side and support each other. To give an example, the proper radiological definition of Morbus Paget is tied to several characteristic findings of such visual comparative quality and unimaginable without these terms and their imaginative power.
However, they are not used as merely spontaneous expressions in a hurriedly jotted down diagnosis report. They are often created in original scientific descriptions of newly discovered diseases and signs and find their way into textbooks and daily use. Some expressions and especially those within the realm of anatomy are eventually integrated into the highly codified nomenclature of medicine, taxonomically recorded and canonically stipulated. This ensures a formalisation in order to structure vision and classify what can and has been seen. This school of vision is eventually transformed into a school of knowledge and thus a necessary epistemic framework is established to be able to make reliable, scientifically sound statements. In vision-oriented specialties, these pictorial comparisons take the role of classic, visual diagnosis, i.e. such findings that are predominantly or exclusively made on the basis of visual information. These visual diagnoses usually strike the trained eye and are of such characteristic nature that several diagnostic and therapeutic consequences immediately follow them. Visual comparisons are not only linguistic embellishment, but powerful statements.
Albeit, a structured overview and an epistemic as much as a stylistic study of visual comparative expressions in medicine is due. To this end, I keep a dictionary and an image database of comparative vision in medical diagnostics of about five hundred expressions ranging from “acetabulum” to “zebra body myopathy”. This collection already suggests that pictorial comparisons in medical diagnostics are not just an isolated phenomenon, but possibly the language and centuries spanning manifestation of medical science led by visual clues which strives to juxtapose the images it produces with linguistic equivalents.
1 Juxtaposition of honeycomb pattern and ground-glass opacity of the lung in computed tomography
2 Coffee-bean sign indicating the contortion of air-filled intestinal loops