The ñ sign is a recently described histopathological visual clue that is useful in the diagnosis of psoriasis vs other inflammatory dermatoses.1 The ñ sign is a visual analogy based on the combination of two well-known histological criteria of psoriasis: on the one hand, acanthosis and regular elongation of the rete ridges and dermal papillae, resembling a lowercase letter “n”; on the other hand, detachment and separation of the lamellar and parakeratotic stratum corneum from the remainder of the epidermis, a common phenomenon during the processing and fixation of psoriasis biopsies, resembling the wavy diacritical mark (tilde) above the Spanish letter “ñ”.2

Thinning of the suprapapillary epidermis with attenuation of the granular layer, as well as dilation and tortuosity of the capillary vessels within the dermal papillae, are, among others, histopathological changes widely identified in the elementary lesions of psoriasis.3

In the 19th century, Alphonse Devergie (1798–1879) and Ferdinand von Hebra (1816–1880) described in the now classic clinical sign for the identification and recognition of the elementary lesions of psoriasis: easy, “en bloc” detachment of the silvery scale followed by a tendency toward pinpoint bleeding when the surface of the lesions is scraped. Heinrich Auspitz (1835–1886), a distinguished pupil of Hebra, did not describe this sign, but rather related it to the typical histological findings of psoriasis mentioned above.4,5 Finally, Jean Darier (1856–1938) coined the eponym “Auspitz sign,” which is widely used in contemporary academic dermatology.6

Thus, from a histopathological standpoint, the ñ sign may be considered the explanation or clinical correlate of Auspitz sign. The ease with which the scale detaches (or “candle-grease sign”) corresponds to the wavy diacritical mark of the ñ sign (separation of the lamellar and parakeratotic stratum corneum). The underlying thin, erythematous, shiny membrane (Duncan-Dulckley membrane) would correspond to the typical thinning of the suprapapillary epidermis resulting from rapid epidermal turnover, which causes loss or reduction of the granular layer. The tortuous and dilated capillary vessels present within the elongated dermal papillae are therefore covered by an extremely thin epidermal layer. This is why scraping psoriatic lesions so readily reveals the pinpoint bleeding of Auspitz sign.

Of note, in contemporary dermatology, psoriasis is not only a therapeutic and research challenge, but its diagnosis can sometimes be challenging. Clinical and histopathological clues or hints remain fundamental in everyday medical practice. Their proactive search during clinical examination or at the microscope, along with clinicopathological correlation, continues to be the reference standard for the diagnosis of most skin diseases.