microcystic adnexal carcinoma ( mac ) is a rare malignant cutaneous neoplasm with pilar and eccrine gland differentiation .
mac was first described as a separate clinical entity by goldstein et al in 1982 .
it is locally aggressive but rarely metastasizes , usually presenting as a slow growing asymptomatic lesion on the head and neck .
fewer than 300 cases have been reported worldwide , according to an analysis by yu et al .
a 67-year - old man presented to a primary care skin cancer clinic in melbourne , australia for a routine six - month skin cancer examination . there was a long history of recreational sun exposure .
seven separate basal cell carcinomas had required excision from his forehead , nose , pinna , posterior neck , mid back calf in the last decade .
most recently a moderately differentiated squamous cell carcinoma had been excised from his right upper forehead some six months previous .
a whole body skin examination was undertaken with the aid of a heine delta 20 non - polarizing dermatoscope ( heine optotechnik , herrshing , germany ) .
digital clinical and dermatoscopic images were taken with a medicam 800 fotofinder non - polarizing camera ( fotofinder systems gmbh , aichner , birnbach , germany ) , the dermatoscopy images being at 20 magnification .
examination confirmed fitzpatrick skin type 2 with severe actinic damage to the skin of his face , upper trunk and distal limbs with multiple solar lentigines and actinic keratoses .
significant actinic damage to the lower lip ( actinic cheilitis ) was apparent . during the examination the patient pointed out a white , scar - like lesion on his mid left cheek measuring 8  4 mm in diameter .
it was non - pigmented and was composed of a clearly demarcated flat white plaque ( figure 1 ) .
dermatoscopically the lesion exhibited a dense white structureless area with fine linear branched blood vessels centrally .
a notable feature was the white clods of variable diameter superiorly ( figure 2 ) .
eccrine syringoid carcinoma , a rare malignant cutaneous adnexal tumor , should also be included in the differential diagnosis .
an excisional biopsy was performed using an elliptical excision , and the specimen was submitted for assessment by a specialist dermatopathologist .
examination of the histological sections revealed a deeply invasive dermal neoplasm composed superficially of keratin filled cysts with calcification , and in the underlying reticular dermis , of infiltrative aggregates of basaloid cells in slender strands and syringomatoid aggregates .
the differential diagnosis was between a microcystic adnexal carcinoma and a fibrosing basal cell carcinoma with follicular differentiation .
this staining pattern , although not entirely specific , was more in favour of microcystic adnexal carcinoma than fibrosing basal cell carcinoma .
ber - ep4 expression has been noted in 38% of microcystic adnexal carcinomas and 100% of basal cell carcinomas .
however ck15 is expressed in 92% of microcystic adnexal carcinomas , whereas basal cell carcinomas are negative .
hence , in conjunction with the positive cea , the findings favoured a microcystic adnexal carcinoma ( figures 3 to 11 ) .
a search of the literature has not discovered any previously published dermatoscopy images of a microcystic adenexal carcinoma .
the two most notable dermatoscopic features of the lesion we present were the dense white structureless area centrally and the white clods of variable diameter peripherally .
white clods of this pattern have also been observed in the more common adnexal skin tumor trichoepithelioma and may represent keratin retention cysts .
microcystic adenexal carcinoma is currently considered a rare tumor . however , such rarities will present more often as the world population increases in age and has increased access to modern medicine .
the authors feel it is important to publish such dermatoscopic images as ours to as wide an audience as possible to aid clinical diagnosis in future .
 we present a case report of a microcystic adnexal carcinoma on the cheek of a 67-year - old man . 
 clinical , dermatoscopic and dermatopathologic images are presented . 
 a search of the literature has not discovered any previously published dermatoscopy images of microcystic adenexal carcinoma . 