an 18-year - old thai woman came to our outpatient clinic with a lump on her right knee . the mass had first been noticed 1 year before and had grown slowly without regression . the patient had gone to another hospital prior to this visit and a needle aspiration had been performed without and content being obtained from the procedure . physical examination revealed a solitary well - defined bluish mass , approximately 5.0  3.0  0.5 cm in size , with firm consistency located on the right knee ( fig . a skin biopsy was done in which the hematoxylin and eosin - stained section displayed increasing components of blood vessels and mature eccrine glands in the mid to deep dermis ( fig . the section showed positive staining with d2 - 40 , cd31 and anti - ulex europaeus-1 , whereas the staining result for glut-1 was negative . the magnetic resonance imaging result showed an enhancing cutaneous nodule with surrounding subcutaneous tissue edema . since the patient complained of an increasing intensity of pain when she came back for follow - up , she was referred to a surgeon for mass excision . eah may occur as a result of an abnormal interaction between the differentiated epithelium and the mesenchyme , leading to atypical proliferation of eccrine and vascular elements . nevertheless , sudoriparous angioma was later discussed by some authors as another distinct entity since it showed dilatation instead of proliferation of the eccrine structures . eah is primarily a disease of the young , with onset usually during childhood and adolescence . in recent years , however , there has been a rising number of cases reported as adulthood eah in the literature . the color of the tumor varies individually from flesh - colored , yellow - brown to bluish . both features have therefore been valued as clues for diagnosis . in general eah is asymptomatic , but associated pain may occur . a histopathological hallmark is the proliferation of eccrine and vascular structures , capillaries in particular . the level of pathology is often located in the mid to deep dermis ; the epidermis is usually unremarkable . nerves may sometimes be observed from the section and its presentation is associated with pain symptoms . the criteria for the diagnosis of eah were proposed by pelle et al .   as follow : ( 1 ) hyperplasia of normal or dilated eccrine glands , ( 2 ) close association of the eccrine structures with capillary angiomatous foci , and ( 3 ) variable presence of pilar , lipomatous , mucinous and/or lymphatic structures . some anecdotal cases of eah with verrucous epidermal hyperplasia as well as features overlapping with hemangioma have been reported . the secretory portions of the eccrine gland show positivity for s100 , cam 2.5 , anti - ema and anti - cea , whereas the ductal portions can be labelled by anti - cea , cytokeratin and anti - ema . factor viii - related antigen and anti - ulex europaeus-1 are useful for identifying the vascular components . the main differential diagnoses for eah are other vascular malformation , blue rubber bleb nevus , tufted angioma , glomus tumor and smooth muscle hamartoma . botulinum toxin injection has been reported to show satisfying result in lesions accompanied by hyperhidrosis .
eccrine angiomatous hamartoma is a rare hamartoma that usually affects childhood and adolescence . in this report 
 we describe a typical onset and clinical presentation of eccrine angiomatous hamartoma . 
 histopathological analysis and immunohistochemical staining of the sections were done to confirm the diagnosis .