the disease is often limited to the epidermis and mucosa , without invasion . in rare instances , empd is reported to become invasive , occasionally infiltrating the dermis and even be highly metastatic to the regional lymph nodes and distant sites . factors such as dermal invasion , involvement of regional lymph node , and distant metastases are indicators of poor prognosis and closely related to the management of the disease . fluorodeoxyglucose ( fdg ) positron emission tomography / computed tomography ( pet / ct ) is of proved value in nodal staging and detection of distant involvement for malignant tumors . however , to our knowledge , the value of fdg pet / ct on evaluating empd has occasionally been reported in the literature . in this report , we describe a case of an old man with extensive invasive empd , in whom f-18 fdg pet / ct was valuable in assessing the extension of the disease and detecting distant metastases . a 64-year - old chinese man presented with a slowly progressive , ill - margined erythematous lesion with a crusted , eroded , and scaly surface involving multiple sites of penis , scrotum , left pelvic wall , hip , groin , and thigh for > 4 years , which became extensive in the past 1 year ( figure 1 ) . he also complained of swelling in the left thigh for > 3 months and a history of muscular atrophy of disuse in the right leg due to encephalitis when he was 2 years old . he was admitted with complaints of progressive pain in shoulder , chest , and back for nearly 2 months duration . ill - margined infiltrative erythematous lesion with a crusted , eroded , and scaly surface is covering on the extensive sites of penis , scrotum , left pelvic wall , hip , groins , and thigh . he was referred for an f-18 fdg pet / ct imaging to further evaluate the lesions . whole - body pet / ct imaging was performed 60 minutes after the intravenous injection of 370mbq ( 10mci ) f-18 fdg and 8 hours fast using a pet / ct scanner ( discovery st-16;general electric medical systems , milwaukee , wi , usa ) . the anteroposterior 3-d maximum intensity projection ( figure 2a ) image demonstrated extensive and invasive abnormal fdg - avid lesions in the body . selected coronal ( figure 2b ) and transaxial ( figure 2c  m ) views of ct ( left column ) , pet ( middle column ) , and pet / ct ( right column ) fusion images revealed mild fdg uptake at the extensive cutaneous lesion with subcutaneous invasion ( figure 2b  e ) , involvement of lymph nodes ( figure 2 f i ) , and multiple intense fdg - avid of skeletal metastases ( figure 2j  m ) . it was highly suggestive of malignancy , and a provisional diagnosis of advanced cutaneous malignancy was made . whole - body fdt pet / ct images demonstrated the presence of multiple fdg - avid lesions in the ( a ) anteroposterior 3d - mip . the selected ( b ) coronal and ( c  m ) transaxial images revealed mild fdg uptake at the extensive cutaneous lesion with ( b  e ) subcutaneous invasion , involvement of ( f  i ) regional lymph nodes , and ( j  m ) multiple intense fdg - avid of skeletal metastases . 3d - mip = 3-dimensional maximum intensity projection , fdg = fluorodeoxyglucose , pet / ct = positron emission tomography / computed tomography . these appearances of fdg pet / ct were not unique to empd and could also be seen in other cutaneous malignancies , even in an inflammatory or infective disease . therefore , biopsy of the fdg - avid lesion was suggested to make a differential diagnosis . hematoxylin and eosin stain showed that the tumors were composed of cells with prominent nuclei and abundant lightly stained cytoplasm ( suggesting paget cells ) ( figure 3 ) . hematoxylin and eosin stain ( 200 ) showed that the tumors were composed of cells with prominent nuclei and abundant lightly stained cytoplasm ( suggesting paget cells ) . empd has been traditionally managed with surgery , especially in the early stage of this disease . in our case , wide local excision is not appropriate because of the advanced stage of the disease that was successfully assessed by fdg pet / ct imaging . the use of radiation therapy was considered in this case . after receiving 4 weeks of radiotherapy , the patient suffered from anemia , hypoproteinemia , and sustained high fever probably caused by systemic metastases and died from complications 2 months after the last dose of radiotherapy . institutional approval was given by the head of the department , and informed consent was given by the patient . empd is a rare cutaneous , intraepithelial adenocarcinoma involving primarily the epidermis but occasionally extending into the underlying dermis . the clinical features of empd can be nonspecific and that misdiagnosis as an inflammatory or infective condition ( eczema , psoriasis , or moniliasis ) is very common . it was originally described in 1889 by crocker , and it is most often observed in areas of apocrine gland - bearing , including the scrotum , penis , vulva , and perineal and perianal region . other rare sites of involvement , such as eyelids , axilla , external auditory canal , and prostate have been reported . empd is often limited to the epidermis and mucosa ; however , it can also become invasive , infiltrating the dermis and even metastasizing to the regional lymph nodes and distant sites , which is also uncommon . factors such as dermal invasion , presence of nodules in the primary lesion , and regional lymph node involvement are indicators of poor prognosis . the prognosis is good when the disease is confined to the epidermis and when it does not metastasize . moreover , empd is sometimes associated with a concurrent underlying internal malignancy in nearly 20% of cases . therefore , a thorough search for the metastatic lesions and underlying malignancy should be recommended before the treatment of empd . whole - body f-18 fdg pet / ct has the ability to identify foci of abnormally high metabolism , and fdg pet / ct has established itself as a valuable noninvasive imaging tool for diagnosing and staging , as well as a prognostic indictor of oncological patients ; however , little is known about the use of fdg pet / ct imaging in evaluation of empd . although increased fdg uptake on skin can also be nonspecific , and it can mimic malignancies ( cutaneous lymphoma , melanoma , and metastases from other internal malignancies ) , and an inflammatory or infective disease , our case indicated that fdg pet / ct is useful in evaluating empd by providing the extent of disease , lymph node involvement , and distant metastases , which is closely related to diagnosis , staging , management , and prognosis of this disease . although the impact of fdg pet / ct on the staging and management of empd should be further evaluated , our case suggested that a whole - body fdg pet / ct should be incorporated into the diagnostic algorithm of empd to give a comprehensive assessment of disease and probably exclude the presence of coexisting internal malignancy .
abstractextramammary paget disease ( empd ) is a rare cutaneous , intraepithelial adenocarcinoma . because of its rarity 
 , little is known about the value of fluorodeoxyglucose ( fdg ) positron emission tomography / computed tomography ( pet / ct ) in evaluating this disease . our case report aims to increase current knowledge of fdg pet / ct in empd as a noninvasive imaging tool for assessing the extension of the disease and detecting distant metastases.we reported a 64-year - old chinese man who presented with a slowly progressive , ill - margined erythematous lesion with a crusted , eroded , and scaly surface involving multiple sites of penis , scrotum , left pelvic wall , hip , groin , and thigh for > 4 years , which became extensive in the past 1 year . 
 he was referred for an fdg pet / ct examination to further evaluate the lesions . 
 a following skin biopsy was performed to obtain a definitive histological diagnosis.fdg pet / ct imaging revealed mild fdg uptake at the extensive cutaneous lesion with subcutaneous invasion , involvement of lymph nodes , and multiple intense fdg - avid of skeletal metastases . according to the appearance of fdg pet / ct , 
 a provisional diagnosis of advanced cutaneous malignancy was made . 
 histopathology findings indicated characteristic of empd . 
 the patient was treated with radiation therapy and died from complications 2 months after the last dose of radiotherapy.our case highlighted that a whole - body fdg pet / ct should be incorporated into the diagnostic algorithm of empd to give a comprehensive assessment of this disease .