Hutchinson sign
Periungual pigmentation; pigmented spread; periungual melanin; "Hutchinson's melanotic whitlow" (historical)
The Hutchinson sign — extension of nail-unit pigment from a band of longitudinal melanonychia onto the adjacent proximal or lateral nail fold — is a classical dermoscopic and clinical red flag for subungual melanoma. It is not pathognomonic: a small number of benign conditions (pseudo-Hutchinson sign) can show similar appearances. However, the combination of asymmetric, widening, dark-brown / black, multicoloured longitudinal melanonychia of a single digit with Hutchinson sign in an adult patient warrants nail-matrix biopsy without delay. Hutchinson described the sign for melanotic whitlow in 1886; the original concept and modern criteria diverge slightly.
Clinical features
- Pigment of the nail unit extending from the nail bed / matrix onto the surrounding proximal or lateral nail fold, eponychium or hyponychium.
- Usually accompanies a band of longitudinal melanonychia (LM) of the same digit — single digit, asymmetric, dark, widening over time.
- Thumb, great toe, index finger most often affected.
- Median age 50–70; both sexes; over-represented in Fitzpatrick IV–VI skin where ALM is proportionally commoner.
- Hutchinson sign in the context of asymmetric or evolving longitudinal melanonychia is a strong indication for nail-matrix biopsy.
Dermoscopy
- Look at the nail plate for the ABCDEF features of LM concerning for melanoma:
- Age 50–70, African / Asian / Native American ancestry.
- Band brown to black, breadth > 3 mm, blurred lateral border.
- Change in nail band rapid.
- Digit thumb > great toe > index, single.
- Extension of pigment onto the nail fold (= Hutchinson sign).
- Family / personal history of melanoma.
- Multiple-component pattern within the band, irregular lines, varying colours.
- Periungual dermoscopy — pigment in the nail fold confirms Hutchinson sign.
Pseudo-Hutchinson sign — benign mimics
- Translucent nail-fold cuticle — apparent pigment due to the cuticle being transparent over a dark nail bed; not true pigment of the fold.
- Drug-induced pigmentation — minocycline, hydroxychloroquine, antimalarials, AZT, chemotherapy.
- Ethnic / physiological longitudinal melanonychia — multiple digits in Fitzpatrick IV–VI; pigment confined to nail plate, not extending to fold.
- Laugier-Hunziker syndrome — mucocutaneous lentigines, longitudinal melanonychia of multiple digits with periungual pigmentation. Benign, no malignancy risk.
- Peutz-Jeghers syndrome — multiple-digit melanonychia with mucocutaneous lentigines.
- Onychomycosis — fungal pigmentation, multiple digits, often without true matrix involvement.
- Subungual haematoma — pigment that moves distally with nail growth; resolves over weeks.
Workup and management
- Photograph the lesion to document baseline and monitor progression.
- Take a thorough history — duration, change, trauma, drug exposure, family history.
- Nail-matrix biopsy under digital block — punch biopsy of the matrix or longitudinal excision biopsy of the LM band including the matrix.
- Specialist dermatopathology review of nail-matrix biopsies is essential — interpretation is challenging.
- If subungual melanoma confirmed — staging investigations and definitive surgery per subungual melanoma pathway.
- Pseudo-Hutchinson confirmed (histology negative) — clinical follow-up; consider repeat biopsy if features progress.
References
- Hutchinson J. Melanotic whitlow of the great toe. Med Times Gaz; 1886 (original description).
- Levit EK et al. The ABCDEF rule for subungual melanoma. J Am Acad Dermatol; 2000.
- Baran R, Kechijian P. Hutchinson's sign — a reappraisal. J Am Acad Dermatol; 1996.
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