Pilomatrixoma was diagnosed with the appearance of basaloid hair matrix cells and eosinophilic anucleated shadow cells
under histologic examination.
Pilomatricomas more often affect younger patients, are characterized histologically by greater numbers of shadow cells
, and tend to be less than 2.0 cm in size.
Pilomatricomas are composed of two types of cells namely basophilic and shadow cells
with areas of calcification (Fig.
If fine-needle aspiration is performed, the diagnosis of PM may be made only if all major components of PM are present in the aspirate, including calcium deposition, basaloid cells and keratinized ghost or shadow cells
. Previous studies show that the diagnostic accuracy rate of preoperatively diagnosing PM ranges from 0-30%, and histopathologic analysis is therefore necessary for a final diagnosis.
There is a study suggesting that apoptosis is the main mechanism leading to the development of the dead shadow cells
and is most probably responsible for the biological behaviour of pilomatricoma.
Histological diagnosis of pilomatricoma is rarely difficult, with characteristic findings showing islands of ghost cells (also known as shadow cells
) surrounded by basaloid cells (Fig.
Finding follicular bulbs, papillary mesenchymal bodies, trichohyalin granules, hair shafts, shadow cells
, and focal CD34 staining in adjacent tumor stromal cells all favor benign entities.
FNA of the lesion commonly reveals basaloid cells, squamous cells, anucleate squames, shadow cells
, foreign-body giant cells, polymorphs, and calcification in variable frequencies.
Tumors are well-circumscribed, dermal to subcutaneous nodules composed of several components, including basaloid proliferation, shadow cells
, dystrophic calcifications, and foreign-body giant-cell reactions (figure 1).
There were squamoid cells with adjacent shadow cells
. Fibro fatty tissue among the seams of bone containing mononuclear, round, poorly differentiated cells approximately twice the size of lymphocytes were observed.
Several nests of shadow cells
, wet keratin and keratin pearls are present [Figure 3].
In the dermis, there were many cystic spaces lined by basaloid cells with shadow cells
on the luminal surface and central eosinophilic areas of keratinization.