Jon A. Reed

Desmoplastic (sclerotic) nevus: an underrecognized entity that resembles dermatofibroma and desmoplastic melanoma.

Desmoplastic (sclerotic) nevus, a benign melanocytic neoplasm characterized by predominantly spindle-shaped nevus cells within a fibrotic stroma, can be confused with fibrous lesions and other melanocytic proliferations, including desmoplastic melanoma. We compared the histologic and immunohistochemical features of 16 desmoplastic nevi, nine desmoplastic melanomas, four hypopigmented blue nevi, and six dermatofibromas. The similarities between desmoplastic nevi and dermatofibromas included epidermal hyperplasia (12 of 16), presence of keloidal collagen (15 of 16), hypercellularity (16 of 16), and increased numbers of factor XIIIa-positive dendritic cells (12 of 12). The absence of adnexal induction (0 of 16), the rarity of lesions with multinucleated cells (3 of 16) or epidermal hyperpigmentation (2 of 16), and the presence of S-100 immunoreactivity (16 of 16) and melanocytic proliferation (9 of 16) helped differentiate desmoplastic nevi from dermatofibromas. The similarities between desmoplastic nevi and desmoplastic melanomas included the presence of atypical cells (16 of 16) and HMB-45 expression in the superficial portion of the lesions (11 of 16). The infrequent location on the head or neck (1 of 16), the absence of mitotic figures (0 of 16), a significantly lower number of Ki-67-reactive cells, and a decrease in HMB-45 expression in the deep area of the lesions (8 of 11) helped distinguish desmoplastic nevi from desmoplastic melanoma. Desmoplastic nevi had overlapping features with hypopigmented blue nevi, but features tending to favor the latter included a predominance of ovoid nuclei, higher numbers of atypical cells, and homogeneous staining with HMB-45. We conclude that a combination of histologic and immunohistochemical criteria facilitates the reliable diagnosis of desmoplastic nevus from its simulators.

Immunohistochemical expression of BCL-2 in melanomas and intradermal nevi

The BCL‐2 gene is the prototype of a newly described family of oncogenes involved in tumorigenesis by blocking apoptosis, or programmed cell death. Overexpression of BCL‐2 protein was originally described in follicular B‐cell lymphomas bearing the 14;18 translocation. BCL‐2 overexpression has also been described in other lymphomas and more rarely in neoplasms outside the lymphoid tissue. The aim of this paper is to determine the immunohistochemical expression of BCL‐2 in intradermal nevi and primary invasive and metastatic melanoma. Formalin‐fixed and paraffin‐embedded tissues from 4 cutaneous melanoma metastases, 10 primary invasive melanomas, and 10 intradermal melanocytic nevi were immimolabeled with monoclonal antibodies directed against BCL‐2 protein (Dako, clone 124) and Ki‐67 antigen (Amac, clone MIB‐1), after antigen retrieval techniques. Morphologically normal epidermal melanocytes expressed BCL‐2, as did nevi and melanomas in virtually all cells. However, whereas the labeling in normal melanocytes and nevus cells showed a uniformly strong reactivity, melanoma cells showed a variable but mainly weak reactivity. Ki‐67 antigen expression was restricted to melanomas. The widespread expression of BCL‐2 suggests that this onco‐protein cannot be involved in the malignant transformation of melanocytic cells. It seems likely that the decreased BCL‐2 expression detected in melanomas may reflect one further step of tumor progression in melanocytic neoplasms.

Expression of the mast cell growth factor interleukin-3 in melanocytic lesions correlates with an increased number of mast cells in the perilesional stroma: implications for melanoma progression

The molecular events responsible for tumor progression in human cutaneous malignant melanoma remain unclear; however, critical to the process is the dysregulated proliferation of tumor cells and the development of new vascular channels which allow further growth and dissemination. Connective tissue mast cells (MC) have been implicated in tumor progression because they concentrate around tumors (including melanomas) prior to the formation of new blood vessels, and because they contain many chemical mediators, including basic fibroblast growth factor (bFGF), known to have mitogenic and angiogenic effects. Several MC chemotactic and mitogenic factors have been described including interleukin‐3 (IL‐3). In order to determine whether there is a differential expression of this MC chemotactic/mitogenic factor with tumor progression in vivo, we evaluated by immunohistochemistry 85 melanocytic lesions including primary invasive malignant melanoma (PIMM), melanoma in situ (MMIS), and ordinary intradermal benign melanocytic nevi (BMN) for expression of IL‐3. Nucleic acid in situ hybridization also was used to evaluate the melanocytic lesions for IL‐3‐specific mRNA transcripts. Intracellular IL‐3 protein was detected in 29/33 (88%) PIMM and 15/25 (60%) MMIS, but was not detected in any (0/27; 0%) BMN (p<0.0001). IL‐3‐specific mRNA transcripts were present in 3/4 PIMM and 2/10 MMIS in which IL‐3 protein was not identified, but were not detected in any BMN. IL‐3 mRNA or protein was not detected in normal melanocytes present in the perilesional epidermis of any of the specimens studied. Immunohistochemistry also was used to confirm the presence of IL‐3α‐specific receptors on human cutaneous MC. As demonstrated by others, a significantly increased number of MC was present in the perilesional stroma of PIMM and MMIS vis à vis BMN (p<0.0001). The results suggest that melanoma cells may attract MC in vivo by producing MC chemotactic/mitogenic factors such as IL‐3. The recruitment of MC and the subsequent release of their potent mitogenic and angiogenic factors such as bFGF may thus represent a tumor–host interaction which favors tumor progression.

The neuropeptide/mast cell secretagogue substance P is expressed in cutaneous melanocytic lesions

Substance P (SP) is a neuropeptide found in both the central and peripheral nervous system. In the skin, SP‐containing neurons stimulate the release of histamine from connective tissue mast cells (MC). SP also can potentiate neoangiogenesis and induce dermal fibrosis. MC‐derived histamine has potent vasoactive effects, is angiogenic, and promotes tissue fibroplasia. In addition to histamine, MC contain many other angiogenic factors and a variety of cytokines, growth factors, and proteolytic enzymes implicated in tissue remodeling, and normal as well as tumor‐associated neoangiogenesis. Many MC‐derived factors, including histamine, can enhance melanoma cell growth directly. MC often concentrate around cutaneous melanomas which also frequently are associated with angiogenesis and peritumoral fibrosis. The precise mediators of these responses have not been well defined. We evaluated by immunohistochemistry cutaneous lesions representing stages of progression of malignant melanoma and its precursor lesions for the expression of SP. SP was expressed in 17/25 (68%) primary invasive malignant melanomas, 2/5 (40%) metastatic melanomas, 6/10 (60%) melanomas in situ, 7/12 (58%) atypical (dysplastic) nevi, and 4/10 (40%) spindle and epithelioid cell (Spitz) nevi, but was not detected in any (0/11, 0%) acquired benign melanocytic nevi (p<0.05). Invasive melanomas were immunolabeled in both the intraepidermal and the dermal components of the lesions. For those atypical and Spitz nevi which expressed SP, most of the immunoreactive melanocytes were located at the dermal‐epidermal junction overlying areas of papillary dermal fibrosis. The results show differential expression of SP among cutaneous melanocytic lesions and suggest that the expression of this neuropeptide together with other factors may contribute to some of the host responses associated with these lesions.

Immunohistochemistry of dermatofibromas and benign fibrous histiocytomas

Dermatofibromas (DF) are common, benign skin tumors composed predominantly of cells having elongated nuclei and very scant cytoplasm (i.e., fibroblasts) and capillaries in a collagenous stroma. Some authors distinguish DF from benign fibrous histiocytomas (BFH), which are composed of cells with round to oval nuclei and abundant cytoplasm (i.e., histiocytes). In general, this group of tumors expresses factor XIIIa but not the antigen recognized by MAC 387. However, immunohistochemical differences specifically between DF and BFH have not been reported.

CD34 immunoreactivity distinguishes between scar tissue and residual tumor in re‐excisional specimens of dermatofibrosarcoma protuberans

Dermatofibrosarcoma protuberans (DFSP) is a locally aggressive tumor that often recurs after simple excision, and therefore usually requires wide surgical re‐excision. It is sometimes difficult to distinguish histologically between residual tumor and scar tissue formed in response to the original biopsy. In an effort to solve this diagnostic problem, we have examined CD34 immunoreactivity in 10 primary biopsies of DFSP, 12 scars, and 7 re‐excisional DFSP specimens containing residual tumor adjacent to scar tissue. In all 10 primary biopsies of DFSP, the tumor cells strongly and uniformly expressed CD34. In the 12 scars, only periaclnexal cells, enclothclial cells, and rare, scattered dendritic cells in the clermis were immunolabeled for CD34. In the 7 re‐excisions of DFSP, the foci of residual DFSP were strongly immunolabeled, while the surrounding scar tissue was not. The pattern of CD34 immunoreactivity distinguishes DFSP from scar tissue, and thereby may permit more accurate assessment of surgical margins in re‐excisional specimens of DFSP.

The intermediate filament peripherin is expressed in cutaneous melanocytic lesions

Peripherin is an intermediate filament involved in growth and development of the peripheral nervous system and is localized to neurons, some other cells derived from neural tube and neural crest, and some neuroendocrine cells (e.g. β cells of islets of Langerhans). Peripherin also has been demonstrated in neuroblastomas and cutaneous neuroendocrine (Merkel cell) carcinomas. The expression of peripherin by other cells derived from the neural crest is unknown.

CD34-reactive fibrous papule of the nose

In human skin, the CD34 antigen is expressed on endothelium, periadnexal cells, and a population of reticular dermal interstitial cells. CD34 expression is characteristic of dermatofibrosarcoma protuberans and several other neoplasms, but not of typical fibrous papules of the nose. We describe a 16-year-old white girl with a slowly growing papule on the nose. Histopathology showed a dermal tumor with a superficial component of branched, thin-walled blood vessels and a deeper component of benign-appearing, spindle-shaped cells. These cells uniformly and strongly expressed CD34, but not factor XIIIa or markers of melanocytic, neural, muscular, vascular, or histiocytic differentiation. We consider this lesion a CD34-reactive fibrous papule. This benign tumor must be clearly distinguished from dermatofibrosarcoma protuberans, which also is composed of bundles of CD34-reactive spindle-shaped cells in most cases but has locally aggressive behavior.

Differential expression of CD44 in malignant cutaneous epithelial neoplasms

The CD44 antigen (ECMRIII, Hermes antigen) is a highly glycosylated cell-surface polypeptide involved in diverse cellular functions, including cell adhesion and lymphocyte-homing receptor activity. CD44 is also expressed in vivo by several tumors, including astrocytomas, menin-giomas, and colonic adenocarcinomas. In addition, it has been shown that expression of CD44 appears to confer metastatic potential to cell lines derived from certain adenocarcinomas. In the skin, CD44 is normally expressed in epidermal keratinocytes and hair follicular, sebaceous, and eccrine epithelial cells. However, there have been few data with regard to the expression in vivo of CD44 in primary cutaneous neoplasms. Furthermore, there have not been studies in vivo of the possible differential expression of CD44 in primary versus metastatic tumors in the skin. We have examined by immunohistochemistry the expression of CD44 in cutaneous invasive and metastatic squamous cell carcinomas, metastatic adenocarcinomas, and basal cell carcinomas. All invasive and metastatic squamous cell carcinomas, as well as metastatic adenocarcinomas, strongly expressed CD44; however, basal cell carcinomas were nonreactive or showed only focal, minimal reactivity. Adjacent normal skin demonstrated CD44 immunoreactivity throughout the epidermis, including the basal layer. In addition, hair follicles and sebaceous and eccrine glands expressed CD44. The results suggest that expression of CD44 in these cutaneous epithelial tumors is not related to malignant transformation, but instead may be related to tumor progression and the ability to metastasize.

Increased expression of basic fibroblast growth factor in squamous carcinogenesis of the head and neck is less prevalent following smoking cessation

Basic fibroblast growth factor (bFGF), a potent angiogenic peptide, is thought to provide a growth advantage to a number of tumors including squamous cancer of the head and neck. The purpose of this study was to demonstrate the in situ expression of bFGF in lesions of the upper aerodigestive tract (UADT) and to correlate that with clinical parameters and known risk factors for carcinoma. On surgical specimens from 52 patients, we used a colorimetric in situ hybridization assay to determine the expression of bFGF mRNA in normal and pathologic conditions commonly seen in squamous mucosa. The extent of reactivity for the bFGF transcript was recorded on a subjective scale from 1+ to 3+, based on the visual intensity of labeling. These findings were subsequently correlated with clinical data. Basic fibroblast growth factor mRNA was detected at low to moderate levels in all sections of normal mucosa, with no distinction between patients with or without squamous cancer. Inflamed mucosa had comparatively strong expression of bFGF mRNA. Among lesions implicated in the stepwise nature of squamous carcinogenesis, we found increases in bFGF expression that were most significant at the level of carcinoma in situ, persisting through the invasive and nodal metastatic stages of the disease (P < 0.005). Interestingly, those increases were significantly less frequent among former smokers (P = 0.02). We have established the expression of bFGF mRNA in normal, inflammatory, and neoplastic tissue within the UADT. Furthermore, we note for the first time that increased expression is associated with the acquisition of more aggressive biologic behavior in squamous carcinogenesis.