Neurofibroma is a benign nerve sheath tumor derived from the peripheral nerve. Its basic pathologic process is a proliferation of the entire ‘neuromesenchyma’, which includes the Schwann cells, endoneurial fibroblasts, perineurial cells, mast cells, and cell types with intermediate features. Clinically, neurofibroma is a solitary, skin-colored, soft papulonodule and ranges in size from 0.5 to 2.0 cm. There are several clinical subtypes in neuro-fibroma, such as localized, diffuse, and plexiform variants. Histopathologically, there are several variants including cellular, myxoid, collagenous, hyalinized, epithelioid, pigmented, granular cell, pacinian, atypical, xanthomatized, with epithelial or rhabdomyxomatous differentiation, dendritic cell with pseudorosettes, and lipomatous neurofibroma.

Eccrine hidrocystoma was first described in 1893 by Robinson. In the present, it is classified into two subtypes: the one is Robinson type representing multiple small cysts, and the other is Smith and Chernosky type, representing a larger solitary cyst. The cause of eccrine hidrocystoma is unknown until now. Robinson suggested a hot environment as an important causal factor. Murayama et al. also reported the possibility of eccrine hidrocystoma as a hamartoma-like disorder from retention of per­spiration. levitra professional

In this case, the histopathologic findings showed typical findings of neurofibroma. Particularly, the adipose cells were focally infiltrated within the lesion. The infiltrative pattern seemed to be related to the replacement of fatty tissue, rather than an engulfment of subcutaneous/periadnexal fat or other artifactual changes. In another part of the lesion, it revealed several cystic structures lined by one or two layers of cuboid cells and it showed positive staining for S-100 and negative staining for vimentin and PAS without evidence of decapitation secretion.

So the biopsy specimen was diagnosed as neurofibroma showing fatty change, concurred with eccrine hidrocystoma. We could find several in­teresting and unusual aspects in our patient. First, it is an unusual case showing intratumoral fat in neurofibroma concurred with eccrine hidrocystoma, although multiple eccrine hidrocystomas developed in various conditions such as Graves’ disease and Parkinson disease had been reported. Second, fatty change in this condition is interesting. Fatty changes have been reported in the normal organ like bone marrow and heart, in the pathologic conditions like fibroepithelial polyp, nevus lipomat- ous superficialis, neurofibroma and melanocytic nevi, and in the peripheral nerve tumors like lipo- fibromatous hamartoma of the nerve and spinal epidural lipomatosis. In recent series, it was reported that lipomatous changes were developed in 6.9% of 320 neurofibromas. William and Choen proposed intradermal nevi with fat increased according to the age of the patient, and Maize and Foster suggested that fat within nevi might be a natural result of aging. They presented that multi- factorial process, such as aging-associated metabolic change and reactive response to chronic irritation, could induce fatty changes. It has been suggested that fatty changes of neurofibroma might be related to senescent change or chronic injury such as shaving, combing, or exposure to ultraviolet radia­tion.  suhagra

Although it is documented that any peri­pheral nerve tumor mentioned above can have intermingled with adipose tissue, we think subtle irritation as a most possible cause of fatty change in our case, because trauma-related change, e.g., ulceration, was observed clinically and histopatholo- gically. Although many hypotheses such as fatty metamorphogenesis of nevus cells, development of adipocytes from mesenchymal elements and pluripotent reticulum cells adjacent to blood vessels have been suggested for pathomechanism of fatty infiltration, the origin of adipose cells is still un­clear. It has been suggested that electron micro­scopic studies might be helpful to confirm the presence of transitional features of fat cells. Third, eccrine hidrocystoma in this case is unusual. Commonly, eccrine hidrocystomas appear as mul­tiple small, translucent, vesiculopapular lesions, and face, especially periorbicular area, is known as a common site. There is no report about eccrine hidrocystoma developing on the scalp as a part of ulcerated papule. Considering the unusual location and clinical shape of eccrine hidrocystoma, a hot environment such as artificial hair drying or chronic exposure to sun light might be related to the development of eccrine hidrocystoma within neuro- fibroma. Also there might be some possibility of pressure effect from neurofibroma as an additional causal factor, but the relationship is not clear and a coincidence cannot be ruled out completely.

In conclusion, we report a case of fatty change in neurofibroma concurred with eccrine hidro- cystoma in a middle-aged woman. We think the fatty infiltration in our case might be brought up by irritation rather than senescent change. Further studies will be required to clarity the pathome- chanisms of fatty infiltration of various pathologic conditions in near future. cialis super active