xeroderma pigmentosum ( xp ) is a rare autosomal recessive disorder characterized by cutaneous photosensitivity , pigmentary changes , photophobia and propensity to develop early malignancy in sun - exposed skin and ocular structures .
the malignancies described commonly in patients with xp include squamous cell carcinoma ( scc ) , basal cell carcinoma ( bcc ) , and malignant melanoma ( mm ) . other types of cutaneous neoplasm including angiosarcoma and fibrosarcoma have also been reported .
atypical fibroxanthoma ( afx ) is a pleomorphic spindle cell neoplasm of the dermis that occurs in actinically damaged skin of elderly individuals .
however , cases also have been reported occurring in the limbs and trunks of younger persons .
histologically , it mimics malignant fibrous histiocytoma ( mfh ) , but the tumor usually follows an indolent or locally aggressive course . only a small number of metastatic cases have been reported .
afx has been regarded as the neoplasm of low - grade malignancy related to mfh .
a 20-year - old man , farmer by occupation , presented with two tumors over his cheek . on examination , the patient showed pigmentation and depigmentation all over his body [ figure 1 ] which , according to him , were present since childhood . on further enquiry , he gave a history of six operations on his face over the last 4 years . on three occasions ,
the lesions were diagnosed as baso - squamous carcinoma , once as scc , and on two occasions he developed bcc .
he had five siblings out of which two were affected by the same disease process and died of metastasizing scc .
the other three , all younger to him , were phenotypically normal with no manifestation of the disease so far . during the present visit , two tumors were excised from his cheek . on gross examination ,
one of the tumors measured 3.5  2  2 cm and showed ulceration of the skin surface .
sections showed a relatively well - circumscribed mass with tumor cells occupying papillary and reticular dermis .
the tumor cells comprised polygonal- to spindle - shaped cells with bizarre and multinucleated tumor giant cells showing marked pleomorphism [ figure 3 ] .
mitotic figures were present but not brisk . with the differential of a poorly differentiated epithelial neoplasm and a soft tissue tumor in mind , immunohistochemistry was performed and the cells showed strong positivity for vimentin [ figure 4 ] , and were negative for pancytokeratin , s-100 and hmb45 .
the tumor cells also showed positivity for cd68 [ figure 5 ] , suggesting a histiocytic differentiation .
taking into account the gross , histomorphologic , and immunohistochemical features , a diagnosis of afx was made . in the 8-month follow - up period , the patient did not develop any metastases
. mottled pigmented and depigmented areas of facial skin along with scars of previous surgeries photomicrograph showing a well - circumscribed dermal neoplasm with intact epidermis ( hematoxylin and eosin , 40 ) photomicrograph showing highly pleomorphic spindle - shaped cells with bizarre giant cells ( h and e , 400 ) photomicrograph showing tumor cells expressing vimentin ( immunohistochemistry for vimentin , 400 ) photomicrograph showing tumor cells expressing cd68 ( immunohistochemistry for cd68 , 400 )
xp is an autosomal recessive disorder characterized by defective deoxyribonucleic acid ( dna ) repair .
the skin cells from patients with xp have an impaired ability to repair ultraviolet ( uv)-induced dna damage .
defective dna repair is also reflected in dermal fibroblasts , lymphocytes of peripheral blood , and conjunctival cells .
xp being an autosomal recessive disease , the heterozygous parents are normal and both the sexes are equally affected . in the present case , out of five siblings of the patient ,
two were affected by the same disease process and succumbed to repeated development of scc .
malignant skin neoplasms have been reported in 45 - 60% of xp patients in different studies .
robbins has shown 10 - 20 times higher incidence of internal neoplasm in xp patients compared to normal controls .
. only five cases of fibrosarcomas , three angiomas , two afx , two mfh , and one angiosarcoma have been demonstrated so far.[131012 ] the histogenesis of afx is controversial .
however , electron microscopic and immunohistochemical studies indicate that as for mfh , the progenitor cell is an undifferentiated mesenchymal cell , capable of showing histiocytic , fibroblastic , and myofibroblastic differentiation .
the concept that afx is a form of pleomorphic mfh has received further support from a study in which no significant difference between afx and mfh was demonstrated in their apoptotic behavior , proliferation indices , p53 protein expression and presence of the bcl2 product . despite marked cytological atypia , dilek et al . have found few mitotic figures in afx .
however , other studies have shown numerous mitotic figures including abnormal forms . despite its apparently malignant histologic features
, the tumor usually follows an indolent or locally aggressive course . due to the small number of metastatic cases reported
, afx has been regarded as the neoplasm of low - grade malignancy related to mfh from which it is indistinguishable histologically . according to this view ,
the more favorable prognosis of afx is related to its superficial location and small size .
the data regarding the outcome of afx are mostly available from the cases not associated with xp .
the outcome of the cases of afx in patients with xp has not been discussed in literature .
the differential diagnosis in the present case , occurring in a patient of xp , included a poorly differentiated epithelial neoplasm .
immunohistochemistry for cytokeratin , s100 , vimentin , and cd68 helped confirmation of the diagnosis .
dilek et al . have recommended cytokeratin , s100 , hmb45 , and histiocytic markers in difficult cases .
cases of afx are usually associated with severe actinic damage and few have arisen in areas treated by radiation .
deficient repair of uv - induced dna damage is directly involved in the development of cancer in xp .
 xeroderma pigmentosum ( xp ) is a rare autosomal recessive disorder related to defective deoxyribonucleic acid ( dna ) repair . 
 various cutaneous manifestations related to ultraviolet ( uv ) damage characterize the clinical course . 
 primary malignant cutaneous neoplasms like squamous cell carcinoma , basal cell carcinoma and malignant melanoma have been reported . 
 atypical fibroxanthoma is a rare dermal neoplasm occurring in uv - damaged skin . 
 we report an unusual case of atypical fibroxanthoma in a 20-year - old male with xp . 
Introduction
Case Report
Discussion