Abstract
Evidence on eccrine porocarcinoma (EPC) was revised in response to the case of a 74-year old patient, presenting with an EPC located in the breast and initially treated with local excision only. She was referred to our center after loco-regional recurrence, but re-excision with lymphadenectomy and adjuvant radiotherapy to a dose of 66 Gy failed to obtain loco-regional control. EPC is a rare disease, occurring in 0.005-0.01% of all skin cancers. The probability of misdiagnosis is high, especially in case of an unusual primary site of tumour location. Clinical and histological diagnosis encompasses a large list of differential diagnoses. Treatment primarily consists of surgery, with lymphadenectomy in case of unfavorable characteristics. No evidence exists for adjuvant systemic or loco-regional treatment.
Highlights
A 74-year old patient, diagnosed with an eccrine porocarcinoma (EPC), primarily localized in the breast, was referred to our hospital.Two years earlier she underwent a lumpectomy for a polypoid nodule in the right breast at her local hospital
Squamoid variants of EPC may be difficult to differentiate from squamous cell carcinoma but squamous cell carcinoma lacks ductal structures and intracytoplasmic lumina, which can be highlighted with the immunohistochemical EMA and CEA staining
An invasive breast ductal carcinoma can be added in the differential diagnosis, as an EPC presenting in the axillary lymph nodes or in the breast is hard to differentiate from a primary breast carcinoma
Summary
A 74-year old patient, diagnosed with an eccrine porocarcinoma (EPC), primarily localized in the breast, was referred to our hospital. A second FDG-PET-CT five months later revealed lesions in skin, bone, lungs and lymph nodes Another case was reported in 2007, confirming correct diagnosis of metastases using FDG-PETCT [18] and a similar third case was described in 2014 by Golemi et al [19]. Squamoid variants of EPC may be difficult to differentiate from squamous cell carcinoma but squamous cell carcinoma lacks ductal structures and intracytoplasmic lumina, which can be highlighted with the immunohistochemical EMA and CEA staining In this particular case, an invasive breast ductal carcinoma can be added in the differential diagnosis, as an EPC presenting in the axillary lymph nodes or in the breast is hard to differentiate from a primary breast carcinoma. Based on the morphology (connection of the tumour to the epidermis and the ductal eccrine differentiation) and the immunohistochemistry (negativity of CK7, ER, PR and GATA3) of the present case, the diagnosis of a primary breast carcinoma was unlikely.
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