Hidradenoma Rare cutaneous condition on MRI

A 34-year-old female presented with history of hidradenoma operated and soft tissue swellings in the presternal location.   The CEMRI characterizes lesions as two, large well-defined, regular, circumscribed, intensely and heterogeneously enhancing components with bleed (T1 hyperintensity) in the left, with enhancing irregular mural nodules, differential enhancement with subtle marrow edema of the sternum with no regional lymphadenopathy,  retrosternal extension, consistent with recurrence  or malignant transformation.

Teaching points by Dr MGK Murthy,  Dr Srinivas Mehta & Mr Ratnakar:-

1. Clear cell hidradenoma is rare skin appendage tumor (sweat gland). 4^th to 8^th decades of age with females more than males is common.  Sweat glands are of 3 varieties – Eccrine (clear cell variety from this), Apocrine & Mixed

2. Slow growing and solitary usually. Head, face and extremities are common locations.

3. Radiology is non-specific and could help characterize, show extent  and distant involvement.  Solid and cystic components with enhancing mural nodules of irregular shapes on MRI. 

4. Mostly benign, can turn malignant, particularly after inadequate excision. Metastases to lymphnodes, bones and lungs can occur.

5. FNAC is not conclusive. Wide surgical excision with negative surgical margins and adjuvant RT and  CT advocated.  Local recurrence is high.