Triphalangeal thumb

Case contributed by Ashesh Ishwarlal Ranchod
Diagnosis certain

Presentation

Elongated thumbs since birth. The thumbs appear finger-like bilaterally. There is an absence of any known congenital syndromic disorder at the time of presentation

Patient Data

Age: 5 months
Gender: Female
x-ray

Triphalangeal thumbs bilaterally with an extra middle phalanx.

The extra middle phalanx has a somewhat trapezoidal shape bilaterally.

The ossification center of the additional middle phalanges has yet to develop.

The hands are otherwise normal.

Image courtesy: Dr Amaresh I Ranchod.

Case Discussion

A case of a rare anomaly1, specifically, a triphalangeal thumb (TPT) bilaterally.

A unilateral presentation may imply a sporadic or isolated deformity while bilateral deformities may imply a syndromic/ familial etiology, often dominantly inherited 1.

There are over twenty known associated congenital syndromes, including but not limited to Fanconi anemia, Holt-Oram syndrome, Poland syndrome, Patau syndrome, and Vater association.

Classification of the TPT is based on the shape of the extra middle phalanx, specifically, wedge, trapezoidal, or rectangular 1. The thumb length will vary based on the extra middle phalangeal size 1.

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