In the new classification of adenocarcinomas, the term lepidic is defined as tumor cells proliferating along the surface of intact alveolar walls without stromal or vascular invasion.[...] This word is a neologism, a new word invented in Canada in the early 1900s [by] John George Adami, MD. [...] After studying in Manchester, Cambridge, Breslau, and Paris, Dr Adami arrived at McGill University in Montreal, Canada, in 1892. Adami was a prolific writer, and he first used the term lepidic in an address to the Toronto Pathological Society on January 4, 1902. In his lecture titled ‘‘Original Communication on the Classification of Tumors,’’ he proposed 2 new terms that would be used to classify all neoplasms. The term lepidic (from greek meaning a rind, skin, or membrane) was applied to tumors that appeared to be derived from surface-lining cells. The term hylic (from greek meaning crude undifferentiated material) was applied to tumors that appeared to be derived from connective tissues. [...]
[...] The terms lepidic and hylic underwent a subtle change in meaning. In Herbert Spencer’s Pathology of the Lung,6 published in 1962, he stated that tumors may grow into the surrounding alveoli ‘‘either filling them with a solid mass of malignant cells (a hilic [sic] growth) or lining their walls (a lepidic growth).’’ This is a minor alteration in definition; however, this is where the modern definition of tumor growth along intact alveolar septa arose. [...]
In the early 1990s the erroneous belief that the term lepidic came from the etymologic origin ‘‘butterfly’’ became prevalent. [...] Soon the term was stated to mean, ‘‘like a butterfly resting on a branch,’’ ‘‘resembling butterflies sitting on a fence,’’ ‘‘butterflies alighting on shrubbery,’’ ‘‘vague resemblance in cross-section to a butterfly,’’ and a reference ‘‘to the scales of the butterfly wing.’’ While these colorful and useful metaphors evoked both the microscopic morphologic appearance and the possible aerogenous mode of dissemination, they were unrelated to the source of the term. Lepidic did not have an entomologic etymology.
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John George Adami (left) first chair of pathology at McGill University (Montreal, Canada) and creator of the term lepidic. Lepidic pattern of adenocarcinoma, characterized by noninvasive surface alveolar growth of tumor cells (right).
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