Rare Conditions Tumor

Nora Lesion

A Nora Lesion is also knows as a bizarre parosteal osteochondromatous proliferation.  This tumor is a bony outgrowth on the outside of the bone, typically found in the fingers and off of the phalangeal bones.  The sexes are affected equally.  There is an occasional history of trauma but this may not be truly relevant.   This is a benign lesion (meaning it does not spread to other parts of the body) but it does have a high risk of coming back to the same spot after excision (i.e., local recurrence); it can recur in 50% of patients or more.  

This uncommon tumor is often seen in patients in their 20s and 30s but can be seen in adolescents (or younger).  It may be mistaken for a osteochondroma- please see two other mentions- post or 2nd post. It can also be confused with an osteosarcoma (parosteal variety).
Most patients present with a large bump but the size and rapid growth are both concerning and the bump can interfere with function.  Finger motion may be decreased.
Here is the case of a male in his 20s with the presentation of this bump over the previous 2 months.  There is no pain and despite the large size of the mass, his hand function was good.  
Clinical picture of index finger mass.  A Nora Lesion.

Radiographs were taken and an aggressive appearing mass is identified.

Nora lesion, view 1.

Nora Lesion, view 2.
Nora Lesion, AP view.

The patient was electively treated with surgical excision of the mass.  The pathology was confirmed as a Nora Lesion.   He will be followed closely over the next several years with clinical checks and intermittent x-rays.  Function is back to normal and he was back to work full duty by 2 weeks.

After removal of the Nora Lesion, radiographs show near normal bone.

Side view after Nora Lesion excision.

Charles A. Goldfarb
My Bio at Washington University

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