Response to 5-Fluorouracil in Metastatic Extramammary Paget Disease of the Scrotum Presenting as Pancytopenia and Back Pain

Abstract

Extramammary Paget disease is a rare intraepithelial neoplasm of the vulvar, penoscrotal, or perianal skin. No effective therapies for metastatic disease have been reported, and prognosis for metastatic disease is poor.Here, we report the case of an Asian man who was initially diagnosed with extramammary Paget disease of the scrotum. Three years later, the patient presented to hospital with pancytopenia and back pain. After an extensive work-up, biopsies of liver and bone marrow revealed adenocarcinoma with signet cells and immunohistochemical staining positive for keratin 7, carcinoembryonic antigen, and prolactininduced protein, but negative for keratin 20, S100, and prostate markers, consistent with his previous biopsyproven Paget disease of the scrotum. The patient was treated with 5-fluorouracil–based therapy in addition to palliative radiotherapy to selected spine levels. A promising palliative response was demonstrated following 5-fluorouracil chemotherapy.A review of the literature on the pathogenesis, diagnosis, treatment options, and outcomes for metastatic extramammary Paget disease is presented.

A case of metastatic adenocarcinoma on a background of penoscrotal extramammary Paget's disease

“…It is frequently misdiagnosed as other benign skin conditions such as seborrhoeic dermatitis, contact dermatitis, lichen sclerosus, Bowen disease, eczema, psoriasis or a superficial fungal infection 2 3 6. It usually appears as a well-circumscribed erythaematous pruritic plaque that can also erode, bleed and form crusts.…”

“…Diagnosis of EMPD is preceded by a high index of suspicion and diagnostic biopsy with immunohistochemistry 2 6. Immunohistochemical tests show a positive staining for CK7, CEA and EMA, as in our case.…”

“…Immunohistochemical tests show a positive staining for CK7, CEA and EMA, as in our case. Some cases have also reported positivity in other markers as well, such as low-molecular-weight cytokeratins (CAM 5.2) and prolactin-induced protein 2 3 6–8. Staining, however, is consistently negative for high-molecular-weight CKs, CK 20, A100 and prostate markers 2 3 8…”

“…Once a treatment plan is set, further investigations are necessary, as EMPD is also associated with cancers of the urethra, bladder, prostate, colon, vagina, cervix or endometrium; one case of hepatocellular carcinoma has also been reported 2 3 6 7. Some publications have even reported the coexistence of EMPD with squamous cell carcinoma, especially in the vulva 6.…”

“…Some publications have even reported the coexistence of EMPD with squamous cell carcinoma, especially in the vulva 6. Penoscrotal EMPD is mostly associated with cancers of the urinary and gastrointestinal tract in approximately 11% of cases, therefore PET-CT or endoscopic investigations are necessary to exclude this presentation 2 3 5…”