Case Discussion (reposted from "introductions")

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Hello everyone,
Long time listener, first time caller.

Brief description of a case that's been referred out to a larger specialty clinic with more resources.

Male 30yo, noticed a small(<5mm) bump on the sole of his foot 6 months prior. Presented to GP 2 months ago after noticing it was visible through his sock.

Examined with patient in dorsiflexion.

Initial exam, the mass is deeply fixated to the anterior of the medial aspect of the plantar aponeurosis, with palpable margins measuring 28mm x 15mm ~8mm raised. The consistency was firm, multilobulated, and the patient expressed mild discomfort when assessing the extent of fixation to adjacent structures. MR with and without contrast ordered.

Post MR follow-up, nearly identical characteristics of the mass, with longitudinal and axial growth. Now measuring 32mm x 15mm x 10mm.

XR interpretation was negative.
MR c-/c+ interpretation was negative.

Familial history of multiple neoplasms:
Sister, amelanotic melanoma, DX'd at 29yo, succumbed to disease in <4 months.
Father, stage IIIC prostatic carcinoma, remission >10yrs.
Grandmother, paternal, unspecified esophagus cancer, deceased.
Uncle 1, paternal, unspecified lung cancer, deceased.
Uncle 2, paternal, unspecified liver cancer, deceased.
Again, the patient has been referred to a larger specialty clinic, but as a learning opportunity, I would appreciate any DDX suggestions, as well as any theories on the unremarkable MR interpretation.

My two theories are;
1) "The wrong camera for the picture", the only available MR was 1.5T.

Or

2) "The drummer had a bad set", an overworked radiologist in a rural setting, and I received his interpretation ~30mins after the patient's exam was scheduled. Seems a little expeditious for the scan, let alone a thorough review?

 

Most likely a fibroma
See: Management of plantar fibromatosis

 

I appreciate the input, and it is good to think horses when you hear the stomping of hooves.

Wouldn't you expect the MRI to detect a well defined fusiform region(or multinodular thickening) with low T1 and T2 signal intensity?

 

From the report,

"Findings:
Bony structures are intact. There is no abnormal contrast enhancement.
In the area of the patient's palpable lump, no mass is seen. No fluid collections identified.
Bony structures are unremarkable. Flexor and extensor tendons of the foot are unremarkable."

 

Worth a call to the radiologist. They mention the palpable lump (I assume they see the lump in the image) but say no mass. That does not make any sense. Fibroma is avascular so would not expect fluid collection.

 

Sorry, I should have included the impression and technical factors from the report when I posted the findings. I'll include them below for context.

"TECHNICAL FACTORS:
MRI of the left foot was performed on the 1.5 Tesla magnet with
multiplanar-multisequence
imaging performed pre and post 20 cc Clariscan. A vitamin E capsule was placed in the area of the palpable abnormality as directed by the patient, along the plantar soft tissues of the foot, at the level of the proximal aspect of the first metatarsal. "

" IMPRESSION:
Unremarkable MRI of the left foot. No mass or fluid collection is identified in the area of the patient's palpable lump."

I was thinking the same thing, and emailed the radiologist, to ask if he would mind taking another look. His response was to copy, paste, and quote his impression from the original report.
At the patient's follow up, I told him that the imaging results were negative. Afterwards, I reexamined the mass, which had grown slightly since my initial exam (two weeks prior), and after a brief discussion with the patient, decided to place the referral.