Presentation
Long-standing, non-painful, erythematous lump in the posterior aspect of the left arm.
Patient Data
Hypoechoic mass, with lobulated and partially defined edges, located in the subcutaneous cellular tissue and in close contact with the triceps muscle, which shows vascularization in color Doppler study.
The MRI sequences revealed a voluminous and polylobulated, mass in the proximal and middle third of the posterior region of the left arm, in the subcutaneous cellular tissue, which involves the dermis and produces displacement of the triceps without clear compromise.
It is of low and heterogeneous signal intensity on T1. It shows intermediate/low signal on T2 and high signal in STIR.
The patient was operated and the tumor and the axillary sentinel node were removed.
After 4 months of the surgery, she consulted again for a tumor of similar characteristics, but smaller, on the front of the right leg.
The MRI shows a polylobulated mass on the anterior aspect of the tibia, in the subcutaneous cellular tissue. It has a low signal intensity in T1 that enhances homogeneously with the intravenous contrast.
Editorial note: The postcontrast acquisition was done without fat supression, which is not recommended for the imaging of soft tissue masses.
Case Discussion
Merkel cell carcinoma is an aggressive skin tumor, with high rates of locoregional recurrence and distant metastases. Its incidence is low. It more frequently affects elderly patients, especially those over 65 years old, with a slight predominance in men.
Its etiopathogenesis is related to ultraviolet radiation exposure and is usually associated with some type of immunosuppression, e.g.. HIV, transplanted, leukemia, lymphoma, and autoimmune disease.
It usually presents as an erythematous, firm, fast-growing and asymptomatic tumor, in sun-exposed areas of the skin.
Because it lacks distinguishing characteristic features, its clinical suspicion is low and generally can be confused with benign lesions. The diagnosis is made through the clinical, histopathological and immunohistochemical study of the lesion.
Surgical removal of the primary tumor constitutes the preferred treatment. The latest recommendation include the histopathological study of the sentinel node when Merkel cell carcinoma is diagnosed for the correct staging.
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