Immunolocalization of extracellular matrix components in mixed tumors of the skin

Running GAGs: myxoid matrix in tumor pathology revisited: what's in it for the pathologist?

Ever since Virchow introduced the entity myxoma, abundant myxoid extracellular matrix (ECM) has been recognized in various reactive and neoplastic lesions. Nowadays, the term "myxoid" is commonly used in daily pathological practice. But what do today's pathologists mean by it, and what does the myxoid ECM tell the pathologist? What is known about the exact composition and function of the myxoid ECM 150 years after Virchow? Here, we give an overview of the composition and constituents of the myxoid ECM as known so far and demonstrate the heterogeneity of the myxoid ECM among different tumors. We discuss the possible role of the predominant constituents of the myxoid ECM and attempt to relate them to differences in clinical behavior. Finally, we will speculate on the potential relevance of this knowledge in daily pathological practice.

Detection and characterization of chondroid metaplasia in canine atrioventricular valves

The atrioventricular valves of 25 dogs of different breeds and age were examined grossly and microscopically following histochemical staining and immunohistochemical labelling for collagen types I, III and VI, and for fibronectin and laminin. Foci of cartilage were identified in the tricuspid septal leaflet within the fibrosa (n=21) or spongiosa (n=3). These were further characterized as either fibrocartilage, predominantly composed of collagens I and VI, or hyaline cartilage consisting of laminin and collagens III and VI. Eighteen of the dogs were of large breed and seven of small breed. Retrospective echocardiographic findings were available from five cases and in three of these a hyperechogenic structure was identified corresponding to the cartilage focus (0.1, 1.12 and 5.63 mm(2) in size). The clinical significance and mechanism of formation of these cartilaginous foci remain undetermined, although factors such as breed, size and concurrent chronic valvular disease may be significant.

Lipomatous mixed tumor with follicular differentiation of the skin

A very rare case of cutaneous mixed tumor with numerous adipose tissue and hair follicular structures in a 67-year-old Japanese male was reported. A well-circumscribed tumor was in the subcutaneous tissue of the cheek and far from the parotid gland. Histologically, the tumor consisted of an admixture of the adipose tissue, fibromyxoid tissue with spindle cells, and branching tubular structures. Outer layers of ductal epithelial cells and single spindle cells were often in a transition, likely as typical mixed tumor. Branching ducts connected with keratinous cysts, strands of trichoblastic basophilic cells and clear cell nests. There was a gradual transition, between small-sized adipocytes and vacuolated spindle cells. No chondroid stroma was seen. To our knowledge, this tumor is the first case of a lipomatous mixed tumor with hair follicular differentiation. The case indicates an additional wide spectrum of histologic appearances of cutaneous mixed tumor.

Bone morphogenetic protein-mediated type II collagen expression in pilomatricoma and cutaneous mixed tumor

BACKGROUND

We have previously reported that type II collagen deposition in overlying dermo-epidermal junction (DEJ) of pilomatricoma is mediated by bone morphogenetic protein 2/4 (BMP 2/4) expressed by shadow cells (SCs) of pilomatricoma.

OBJECTIVE

This time, we studied the expression of type II collagen and BMP in a large number of cases of pilomatricoma and extended our study to cutaneous mixed tumor (CMT).

RESULTS

We found type II collagen deposition in the overlying DEJ (16 of 50 cases) and in the SCs (19/50) of pilomatricoma. The number of case of type II collagen deposition in DEJ (DEJ(+)) and in SCs (SC(+)) of pilomatricoma correlated to the chronological stage of pilomatricoma. We also found type II collagen deposition in overlying DEJ (two of 11) and in the stromal chondroid tissue (four of 11) of CMT. BMP 2 was expressed in most cases of pilomatricoma (37/50) and CMT (seven of 11).

CONCLUSIONS

The expression of type II collagen in pilomatricoma is dependent upon the chronological stage of pilomatricoma. Type II collagen expression in the overlying DEJ and chondroid matrix in CMT may be induced by BMP via the same mechanism as in pilomatricoma.

Chondroid syringoma: an immunohistochemical study using antibodies to Ca 15-3, KA-93, Ca 19-9, CD44 and BM-1

The expression of Ca 15-3, KA-93, Ca 19-9, CD44 and BM-1 in normal skin and chondroid syringoma was investigated immunohistochemically using antibodies to these antigens. In the normal skin, the eccrine ducts and/or secretory elements were positive for all these antigens. On the other hand, the apocrine ducts and/or secretory elements were positive for the antibodies to Ca 15-3, KA-93 and CD44. In chondroid syringoma, the luminal cells of tubuloglandular structures were positive for the antibodies to Ca 15-3 and BM-1, and partly positive for those to KA-93 and Ca 19-9. The basal cells of the tubular structures and solid nests were positive only for the antibody to CD44. Stromal cells in the myxoid area were positive for the antibodies to KA-93 and CD44, and the chondroid matrix was positive for the antibody to BM-1. It is suggested that chondroid syringoma might originate from, or differentiate into the ducts and/or secretory elements of the eccrine sweat glands. In addition, the significance of the expression of BM-1 in the chondroid matrix is discussed.