Age / Sex : 30 / M

Chief complaint: palpable mass, upper arm 2yrs. Rapid enlargmenet during recent 2months

What is your impression?

Two weeks later, you can see the final diagnosis with a brief discussion of this case.

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Courtesy: Tae Eun Kim, Daegu Fatima Hospital

Pilomatricoma

Discussion

Findings:

-   Protruding subcutaneous mass with numerus spotted calcifications on plain radiography.

-       Isointensity compared with skeleltal muscle on MR images(T1WI, T2WI).

-       On T2WI, reticular and amorphous high intense areas are also noted.

-      Rim enhancement and subtle patch internal enhancement.

Differential Diagnosis: Eccrine spiroadenoma

Diagnosis: Pilomatricoma

Discussion: - Known as calcifying epithelioma of Malherbe.

            - Arises in the dermis from cells that normally differentiate toward hair matrix cells.

            - The Face, neck, and upper extremities : most commonly affected.

            - Calcification, which is more typically central : approximately 84% of lesions.

            - Ossification : 20%, more typically peripheral.

            - On MRI, isointense signal compared with skeletal muscle.(T1WI,T2WI)

                     Combined funicular or reticular high intensity area on T2WI.

            - Histopathologically, reticular and amorphous high intense area on T2WI within tumor is corresponding to the area where basaloid cells and ghost cells are abundant within tumor. If the tissues of granulation, fibrosis and calcifications are abundant, signal intensity of tumor on T2WI is more low.

References: 1. Imaging of soft tissue tumors, 2^nd edition

            2. Pilomatricoma:Radiologic findings of 17 cases from ECR 2014/ C-0063