Pollicization of the index finger in Fanconi anaemia: appearances and functionality 40 years after the intervention

Abstract

Fanconi anaemia (FA) is an inherited bone marrow failure syndrome resulting from disruption of a polygenic DNA damage response pathway with variable congenital and developmental abnormalities. Radial ray and thumb abnormalities are classical diagnostic features. These can vary in their clinical severity, but often have significant impact on development and hand usage in later life. Absence or severe hypoplasia of the thumbs can be surgically managed by pollicization with ante-position of the index finger. Very long term outcome and performance in adult life is not well documented. Here we illustrate functionality and appearances of the hands of a 47-year-old woman diagnosed with FA at the age of 3 years because of right thumb absence, severe hypoplasia of the left thumb and thrombocytopenia. Surgery on both hands was carried out shortly after the diagnosis. Clinical documentation from the 1960s and 1970s is unavailable. After completing school she worked in a responsible office-based position. She married, and after several years living abroad, returned to our region and is now followed up in our FA service. She has mild thrombocytopenia with a platelet count of 117 × 109/l, but otherwise normal peripheral blood cell counts with a moderately hypoplastic bone marrow. There is no evidence of mosaicism with persistent FA characteristic G2 arrest spontaneously and with low dose mitomycin C (MMC). At the age of 47 years her hands appear as illustrated. Frequent and purposeful use of the pollicized index finger generated a thenar-like bulk between the opposed index finger and the second finger. Magnetic resonance imaging illustrates the detailed anatomy. Coronal T1 images (A & B) demonstrate normal position of digits 3, 4 and 5 (A – solid arrows) with transposition of the 2nd metacarpal (A – dashed arrow) to create a pseudo 1st metacarpal. The pseudo 1st proximal phalanx (B – dashed arrow) is seen adjacent to a tissue mass placed at the site of the original location of the 2nd metacarpo-phalangeal joint (B – solid arrow). A whole forearm maximum intensity projection from fat- saturated T1 weighted images (C) clearly demonstrates the relationship between the pseudo 1st finger position (dashed arrow), and 3rd, 4th and 5th fingers (solid arrows) with interposed fat (open arrow). Her ante-positioned index fingers had excellent functionality. An illustration of her handwriting is shown in the lower panel (A – insert). To our knowledge this is the longest follow-up ever documented of a pollicization of an index finger in FA, with a very satisfactory long-term outcome.