poroma is a benign cutaneous neoplasm that usually occurs in elderly individuals as a solitary reddish - pink nodule . although divergent adnexal differentiations are occasionally seen in this tumor , poroma with sebaceous differentiation is extremely rare . a 38-year - old japanese female presented with a 2-year history of a slow - growing nodule on her left forearm . physical examination revealed a slightly elevated pink nodule of 4 mm in size [ figure 1 ] . dermoscopically , fine hairpin - like vessels , beige lobular structures were seen in the nodule . of note some of them were too small to be noted as dots , giving orange - beige in color as a whole [ figure 2 ] . histopathologically , the lesion consisted of well - defined nests of monomorphous cuboidal or oval poroid cells with oval nuclei and eosinophilic cytoplasm connected with the overlying epidermis [ figure 3 ] . tubular structures formed by cuticular cells and intracytoplasmic canaliculi in those cells were also present [ figure 4 ] . poroid or cuticular cells were observed in more than 65% area of the tumor cell nests . sebaceous lobules of various sizes were noted in the poroid nest [ figure 5 ] . small yellow dots , fine hairpin - like vessels , and beige lobular structures h and e , 20 . some cutaneous neoplasms can exhibit mixed follicular , sebaceous , and sudoriferous differentiation because of the embryological association of these structures . however , sebaceous differentiation is not generally observed in eccrine poroma because eccrine sweat glands arise from a distinct epithelial unit . poroma with sebaceous differentiation is thought to develop in association with a folliculosebaceous apocrine unit . actually , typical poroma without sebaceous differentiation has a predilection to arise on plantar or palmar skin where there are no hair follicles , whereas poroma with sebaceous differentiation usually does not occur in these regions . however , from the concept of folliculosebaceous apocrine unit , we speculate that ours is an apocrine poroma . there have been several previous reports in which dermoscopic features of poroma were discussed . these reports demonstrated characteristic vascular patterns , including glomerular vessels , looped or hairpin - like vessels , leaf and flower - like vessels , and branching vessels . since some sebaceous tumors exhibit yellowish structures on dermoscopy , it is most likely that yellow dots reflect sebaceous lobules in the tumor . thus , when we see yellow structures dermoscopically , we should consider tumors with sebaceous differentiation as a possible differential diagnosis as well as conventional sebaceous tumors . iwasaki et al . first reported the dermoscopic features of poroma with sebaceous differentiation , but , interestingly , yellowish structures were not evident . we speculate that sebaceous cell aggregations in their case were too small in size and number to be detected by dermoscopy . dermoscopic differential diagnosis showing yellowish structures includes sebaceous naevus , sebaceous carcinoma , sebaceous hyperplasia , sebaceoma , sebaceous adenoma , and reticulated acanthoma with sebaceous differentiation . excluding the yellow dots , dermoscopic features in our case accorded with those in poroma and were different from those in the above diseases dermoscopy is now widely used to diagnose many pigmented and nonpigmented skin diseases , including general and common diseases . it still harbors significant possibilities to provide additional information for improving diagnostic accuracy in daily clinical practice , such as lesions with sebaceous differentiation . tumors with sebaceous differentiation , as well as conventional sebaceous tumors , can show yellow structures on dermoscopy .
although divergent adnexal differentiations are occasionally seen in poroma , poroma with sebaceous differentiation is extremely rare . 
 we present here the second case of dermoscopy on poroma with sebaceous differentiation . a 38-year - old japanese female presented with a 2-year history of a slow - growing nodule on her left forearm . 
 dermoscopically , fine hairpin - like vessels , beige lobular structures were seen in the nodule . 
 many small yellow dots were scattered between beige lobular structures , giving orange - beige in color as a whole . on the basis of histopathologic findings , a diagnosis of poroma with sebaceous differentiation was made . 
 some sebaceous tumors are known to exhibit yellowish structures on dermoscopy . 
 tumors with sebaceous differentiation , as well as conventional sebaceous tumors , can show yellow structures on dermoscopy .