Expression and distribution of type VI collagen in gynecomastia

Comparative study of CD34, alpha-SMA and h-caldesmon expression in the stroma of gynaecomastia and male breast carcinoma

AIMS

To address the fibroblastic/myofibroblastic nature of stroma in gynaecomastia and in male breast carcinoma, the expression of CD34, alpha-smooth muscle actin (SMA) and h-caldesmon in the stromal cells was investigated by immunohistochemistry.

METHODS AND RESULTS

Representative archival paraffin blocks were collected from male patients with gynaecomastia (32 cases) and mammary carcinoma (24 cases) between 1984 and 2004 and CD34, alpha-SMA and h-caldesmon were assessed immunohistochemically using a streptavidin-biotin method. Thirty cases of gynaecomastia showed a CD34+, alpha-SMA- and h-caldesmon- immunophenotype with different CD34 staining intensity in the various histological subtypes. Positivity for alpha-SMA and negativity for CD34 and h-caldesmon was found in a case of florid gynaecomastia relating to reactive fibrosis due to previous surgical intervention. Acquisition of alpha-SMA expression by stromal fibroblasts but absence of CD34 staining was identified in 22 cases of male breast carcinoma.

CONCLUSIONS

The immunophenotype of periductal connective tissue stroma in gynaecomastia appears to parallel the phenotype of normal breast stroma. In male breast carcinoma the stromal cell immunophenotype is similar to that of its female counterpart showing myofibroblastic differentiation. However alpha-SMA+ and CD34- are not specific to malignancy because such findings are also encountered in reactive fibrosis.

Immunohistochemical expression of type VI collagen in superficial fibromatoses

The expression of type VI collagen was studied immunohistochemically in 26 cases of superficial fibromatoses (palmar, plantar and penile) using an immunoperoxidase method for light microscopic visualization. The polyclonal antibody against type VI collagen used in this study was isolated from human placenta and its specifity was tested by immunoblotting assay. All cases consisted of multiple nodules showing a variable degree of cellularity and fibrosis. Depending on the predominant histological appearance of these nodules, each case was assigned to the three following phases: proliferative, involutional and residual. Morphologically normal palmar and plantar aponeuroses were included as controls. Immunohistochemical findings showed that type VI collagen was present as longitudinal thin fibers in normal palmar and plantar aponeuroses. A differential expression of this collagen was found in the different stages of superficial fibromatoses. Type VI collagen was markedly expressed as a distinct fibrillar network in the extracellular matrix (ECM) surrounding proliferating stromal cells in proliferative and involutional phases. Its expression completely disappeared from the connective tissue undergoing fibrotic transformation during involutional and residual phases. The results of the present study suggest that type VI collagen is an extracellular marker of stromal tissue proliferation and is involved in the early phases of tissue remodelling occurring in the superficial fibromatoses.