ABSTRACT
Pleomorphic fibromas represent dome-shaped or polypoid cutaneous lesions characterized by a paucicellular and densely fibrotic background punctuated by scattered atypical to pleomorphic spindle and multinucleated giant cells. Some of these tumors will have incorporated adipose tissue, although these adipocytic areas lack distinct cytologic atypia and may represent entrapped normal periadnexal or subcutaneous adipose tissue. Nonetheless, owing to the similarity of some of the morphologic features of pleomorphic fibroma with cutaneous atypical lipomatous tumor, diagnostic confusion can ensue. The potential diagnostic challenges are further highlighted by a recent report of a lesion with histopathologic features of both. In response, we studied the presence of 12q15/ MDM2 amplification by fluorescence in situ hybridization and MDM2 expression by immunohistochemistry in a series of 15 pleomorphic fibromas to investigate whether these two entities share a common pathogenic origin. One case of cutaneous atypical lipomatous tumor was used as positive control for 12q15 amplification. All 15 cases were negative for MDM2 by immunohistochemistry with no demonstrable 12q15/MDM2 amplification by fluorescence in situ hybridization. Therefore, these two entities are best regarded as pathogenetically distinct. MDM2 immunohistochemistry or fluorescence in situ hybridization studies can be used to differentiate between the two if needed.
Subject(s)
Fibroma/diagnosis , Lipoma/diagnosis , Skin Neoplasms/diagnosis , Adipose Tissue/metabolism , Adipose Tissue/pathology , Adult , Aged , Biomarkers, Tumor/genetics , Biomarkers, Tumor/metabolism , Chromosomes, Human, Pair 12 , DNA, Neoplasm/analysis , Diagnosis, Differential , Female , Fibroma/genetics , Fibroma/metabolism , Gene Amplification , Humans , In Situ Hybridization, Fluorescence , Lipoma/genetics , Lipoma/metabolism , Male , Middle Aged , Skin Neoplasms/genetics , Skin Neoplasms/metabolism , Young AdultABSTRACT
p63, a recently identified homologue of the p53 gene, has been reported to be essential in the development of epithelia and is mainly expressed by basal and myoepithelial cells. The purpose of this study was to investigate the pattern of p63 expression in cutaneous adnexal neoplasms and to assess its possible value in the differential diagnosis of primary cutaneous neoplasms vs adenocarcinomas metastatic to the skin. Immunohistochemical analysis for p63 was performed on formalin-fixed, paraffin-embedded archival tissue from 20 benign adnexal tumors, 10 malignant adnexal tumors and 14 adenocarcinomas metastatic to the skin. The expression of p63 was evaluated in epidermal cells, skin appendages and metastatic tumor cells. p63 was consistently expressed in the basal and suprabasal cells of epidermis and cutaneous appendages, including the basal/myoepithelial cells of sweat glands. Out of 20 benign adnexal tumors, 13 (65%) showed strong (score 3) p63 expression; the remaining seven (35%) cases had score 2. All primary cutaneous carcinomas, including adenocarcinomas, expressed p63. In contrast, none of the metastatic adenocarcinomas to the skin was positive for p63 (P<0.001). Based on our findings, analysis of p63 expression may help in the differential diagnosis of primary vs metastatic cutaneous adenocarcinomas.
