Pathological assessment of pancreatic endocrine tumors for metastatic potential and clinical prognosis

The prognostic significance of several pathological factors (tumor size, mitotic index, Ki-67 labeling index, and vascular invasion) and expression of exocrine markers (CA19-9, CEA, AFP, and trypsin) in pancreatic endocrine tumors was studied. A total of 20 specimens of metastasizing (n=10) and non-metastasizing (n=10) tumors were subjected to histological and immunohistochemical examination. The metastasizing tumors showed significantly larger size, higher Ki-67 labeling index, increased number of mitotic cells, and more frequent vascular invasion in comparison with the non-metastasizing tumors. It was difficult to determine the effect of individual factors on clinical outcome because of slow disease progression in almost all cases. Numerous mitotic cells and widespread necrosis, however, were thought to indicate a poor prognosis, and tumors with these characteristics were regarded as high-grade malignant endocrine carcinomas. In one case, one-third of the tumor tissue comprised trypsin-positive cells, the outcome was comparatively poor, and the behavior of the tumor resembled that of mixed acinar-endocrine carcinoma. A simple multifactorial approach may be effective for the identification of tumors at increased risk of metastasis, but it remains difficult to determine clinical prognosis. It is essential to at least distinguish high-grade endocrine carcinomas from the more common endocrine tumors.     

Immunohistochemical analysis of cyclooxygenase (COX)-2 expression in pancreatic endocrine tumors: association with tumor progression and proliferation

An immunohistochemical study of cyclooxygenase (COX)-2 expression in pancreatic endocrine tumors (PET) was carried out, and the expression of COX-2 was compared with pathological features, the expression of several markers (hormones, vascular endothelial growth factor, single-stranded DNA, and the Ki-67 labeling index [LI]). Twenty PET, including 10 metastasizing cases (tumor size: 3-8 cm) and 10 non-metastasizing cases (tumor size: 0.3-8 cm) were studied. Tumors with a high level of COX-2 expression were placed in the H group, and the remaining tumors were placed in the L group. The H group was comprised of 13 tumors: all 10 of the metastasizing cases and three of the non-metastasizing cases. There were significant differences in tumor size between the two groups (H group 46.5 mm; L group 0.9 mm). There were significant differences in the presence of the following histological criteria for malignancy: pleomorphism (H group 13/13; L group 1/7), mitotic activity (H group 2.9; L group 0) and/or angioinvasion (H group 13/13; L group 1/7); and there were also significant differences in the number of cases that expressed ectopic hormones (gastrin, vasoactive intestinal peptide, serotonin and calcitonin; H group 12/13; L group 2/7) and in the Ki-67 LI (H group 8.3%; L group 0.4%). The distribution of COX-2-positive cells tended to be similar to the distribution of Ki-67-positive cells. Our data show that COX-2 is frequently upregulated in malignant PET and that there is a close relationship between COX-2 expression and tumor progression/proliferative activity.     

Tumor angiogenesis as a prognostic factor in thick cutaneous malignant melanoma

The prognostic value of the extent of neovascularization in cutaneous melanoma is a highly controversial issue. The aim of the current study was to evaluate whether the morphometric analysis of tumor vascularity may be helpful in predicting the clinical outcome of patients with thick cutaneous melanomas. A series of 15 patients with melanoma (>3 mm in thickness) who did not experience disease progression after long-term follow-up (10 years) and 30 matched controls who underwent recurrence and/or metastases were selected for the study. Microvessels were immunohistochemically stained with anti-CD31 antibody. Several parameters, including vessel number, vascular density, vessel area, equivalent circle diameter, perimeter, shape factor, compactness, and the number of vascular ramifications per 100 vessel sections, were quantitatively assessed by a computer-aided semi-automatic image analysis system. Mean vessel area was 341.69 microm2 in cases without progression and 512.55 microm2 in the progressed melanomas (P=0.008, Mann-Whitney U test). The mean equivalent circle diameter was 18.95 microm in non-progressed melanomas and 22.57 microm in progressed melanomas (P=0.009). The mean number of ramifications was 0.8 in cases without progression and 1.9 in the controls (P=0.03). Microvessel count and vascular density were higher in progressed cases (17.37 vs. 11.73 and 28.94/mm2 vs. 19.55/mm2, respectively), but the difference did not reach statistical significance (P=0.06). Our results suggest that neovascularization is a critical event in the progression of thick melanoma. Its prognostic significance is better assessed by quantification of vessel area, equivalent circle diameter, and microvessel branching, whereas microvessel count and vascular density do not provide significant prognostic information.     

胰腺实性假乳头状肿瘤临床病理学与恶性转移潜能相关性研究

目的 探讨胰腺实性假乳头状肿瘤(SPT)临床病理学特征和恶性转移潜能相关性.方法 收集45例SPT标本,利用光镜观察其形态学特征并依据形态学综合评分,免疫组织化学EnVision法检测波形蛋白、α-1-抗胰蛋白酶、α-1-抗胰糜蛋白酶、CD10、神经元特异性烯醇化酶、PR、嗜铬粒素A、突触素、AE1/AE3、β-catenin、p53、cyclin D1、CD34、Ki-67表达,将以上结果同临床随访资料(分为非转移组和转移组)进行综合比较分析.结果 非转移组和转移组的年龄、性别、肿瘤部位、肿瘤平均直径和大体包膜情况比较,没有明显差异.单独形态参数(核分级、核分裂象、细胞异型性、血管内瘤栓、渐进性坏死巢、凝固性坏死)并不能区分非转移组和转移组,但核分裂象、血管内瘤栓和渐进性坏死巢在转移组较非转移组更为常见.依据形态学综合评分,非转移组41例中,39例(95.1%)综合得分<5分,转移组综合得分全部≥5分.免疫组织化学非转移组与转移组比较,β-catenin、p53、cycli D1、CD34差异无统计学意义;核增殖指数Ki-67差异有统计学意义.45例SPT患者中,平均随访37.4个月,8例失访,33例无瘤生存,4例发生不同程度的肝转移,目前无死亡.结论 SPT的核分裂象、血管内瘤栓和渐进性坏死巢对于预测肿瘤的恶性转移潜能具有一定的参考意义;形态学综合评分对于预测SPT的恶性转移潜能具有重要价值;核增殖指数Ki-67也具有一定参考价值.     

Papillary cystic tumor of pancreas--report of two cases

Two cases of Papillary cystic tumor of pancreas--one metastasizing to lymph node and the other non-metastasizing are reported for their rare occurrence. Both occurred in young females and presented with heaviness and pain in the left hypochondrium with palpable mass. On radiological examination, mass was arising from tail of pancreas and had typical gross features. The histological findings seen in metastasizing tumor were capsular invasion, infiltration to surrounding pancreatic tissue and vascular invasion with metastasis to lymph node. Difference in nuclear grade or mitosis was not observed. Adjuvant chemotherapy was given for metastasizing tumor and patient is symptom free after 56 month. Non-metastasizing case is well after 15 months.     

The prognostic significance of tumor vascularity in intermediate-thickness (0.76-4.0 mm thick) skin melanoma. A quantitative histologic study.

The vascularity of 20 primary skin melanomas was assessed histologically. These cases were selected from patients with intermediate thickness melanomas (0.76-4.0 mm thick) treated surgically to provide two groups of ten patients. One group had no evidence of recurrence with a minimum follow-up of 9 years. The second group of ten patients developed locoregional or systemic metastasis under follow-up, and seven of these patients died of disseminated melanoma. Age, sex, Breslow's tumor thickness, and Clark's level of invasion were similar in the two groups. Vascular quantitation was carried out by image analysis after vascular definition by Ulex europaeus-I agglutinin staining. The percentage vascular area at the tumor base in the recurrence group was more than twice that in the recurrence-free group. This study suggests that increased vascularity at the tumor base may have prognostic significance in intermediate thickness melanomas.     

Metastatic tumors to the female breast. An autopsy study of 12 cases

Twelve cases of metastatic tumors to the female breast are reported. Ten of them were incidentally discovered at autopsy; two cases were diagnosed ante mortem but one was misinterpreted as primary. The patients' mean age was 58 years. The metastasizing tumors included cutaneous malignant melanoma (four cases); ovarian, renal and gastric adenocarcinoma (two cases each); and individual cases of pulmonary and pancreatic carcinoma. The patients with melanoma were younger than the others (49.7 vs. 62.7 years). The results of the present study indicate that breast metastases, although rare, are not exceptional especially in large autopsy series. Their recognition in surgical material would result in more adequate treatment against the primary tumor, thereby avoiding unnecessary radical surgery to the breast.     

DNA ploidy in thin melanoma

DNA ploidy in benign nevi (BN), thin non-metastasizing melanomas (TNM) and thin metastasizing melanomas (TMM) was investigated using an image analyser to determine whether characteristics such as nuclear area (NA) and nuclear integrated optical density (IOD) could be used to distinguish between these lesions. NA measurements showed significant differences between samples of nevus cells and melanoma cells and nuclear IOD differences were significant between TNM and TMM samples. Differences in NA and nuclear IOD were detected across the three groups (BN, TNM and TMM) but the large variability within samples and within groups indicate further studies would be necessary to determine the usefulness of these results in terms of the rate of correct group classification of a single sample for diagnostic purposes.     

Correlation between tumor vascularity and clinical findings in patients with pituitary adenomas

Angiogenesis generally plays an essential role in tumor growth and metastasis, and also influences the response to treatment in human malignant solid tumors. Even in nonmalignant tumors, angiogenesis is essential for tumor growth and invasion. In order to define the relationship between tumor vascularity and the clinical course in patients with pituitary adenomas, we quantified the vascularity in 47 pituitary adenomas and in 6 normal anterior pituitary glands obtained at autopsy using a computed image-analyzing system. We estimated two parameters, the vascular number and the area as the vascularity. Additionally, we calculated mean individual vessel size using the above two parameters. The relationships of tumor vascularity to clinical, endocrinological and histological findings was assessed. Factors considered included patient age and gender, preoperative medication, histological type, concentration of each hypersecreted pituitary hormone, maximum tumor size, cavernous sinus invasion, intratumoral hemorrhage, and immunohistological results of localization of vascular endothelial growth factor (VEGF). Vascularity was significantly higher in normal glands than in pituitary adenomas. However, there were no significant correlations between tumor vascularity and other clinical, endocrinological, or histological parameters, suggesting that increased angiogenesis is not essential for pituitary adenoma growth or invasiveness.     

The vascularity of primary cutaneous melanoma

In primary cutaneous malignant melanoma, the vascularity of the dermis immediately deep to the lesion may relate to tumour aggressiveness and to prognosis. These newly formed dermal vessels are incorporated into the melanoma to form the tumour microcirculation. We have assessed the percentage vascular volume in a series of primary melanomas in order to investigate the relationship between tumour vascularity and maximum tumour thickness. For the 64 melanomas included in this study, there appeared to be a significant relationship between the percentage vascular volume and the maximum tumour thickness. This relationship was not influenced by the presence of necrosis, vascular invasion, regression, or lymphocytic infiltrate, nor by the growth phase of the tumour. However, the percentage vascular volume was very low in the occasional thick melanoma, at least one of which was associated with prolonged survival. It seems possible that a low tumour vascularity could correlate with a relatively favourable outcome in cutaneous melanoma.     

Association of MYCN amplification and 1p deletion in neuroblastomas with high tumor vascularity.

The biologic behavior of neuroblastoma (NB) is extremely variable; therefore, the clinical behavior may be reliably predicted based on the analysis of a panel of prognostic parameters. High vascular density has been correlated with aggressive tumor progression in many types of cancers. The goal of this study was to correlate the tumor vascularity in NB with status of MYCN and the short arm of chromosome 1 (1p) to address the association between angiogenesis and genetic markers of prognostic significance. The study population consisted of 33 patients with histologically proven diagnosis of primary NB and no history of previous chemotherapy. Histologic quantitation of tumor angiogenesis was performed using 3 different methods: microvessel density, vascular grading, and Chalkley counting. MYCN amplification and 1p deletion were determined by using fluorescence in situ hybridization technique. The differentiation and mitosis-karyorrhexis index of tumor cells were also assessed using the Shimada System. MYCN amplification was present in 12 cases (36.3%), and 1p deletion in 16 (48.5%). Both genetic changes significantly correlated with increased tumor vascularity. In addition, tumor vascularity was significantly increased in tumors with high mitosis-karyorrhexis index or of undifferentiated histology. We conclude that angiogenesis shows close association with histologic and genetic prognosticators in NB. Our data support the validity of recent applications of antiangiogenic agents which interfere or block NB progression.     

Angiogenesis and tumor progression of melanoma. Quantification of vascularity in melanocytic nevi and cutaneous malignant melanoma.

BACKGROUND: The capacity of cutaneous malignant melanoma (CMM) to induce angiogenesis is well established. In addition, dysplastic melanocytic nevi (DMN) have been reported to display prominent vascularity relative to common acquired nevi; but this observation has never been verified objectively. EXPERIMENTAL DESIGN: In the following studies, papillary dermal or tumor vascularity was quantified in 10 examples of normal skin, and in a series of 18 melanocytic nevi, 29 DMN, 37 primary CMM and 5 melanoma metastases. Microvessels were identified with the lectin Ulex europaeus agglutinin I. The number of microvessels were counted with an ocular grid (area 7.84 x 10(-2) mm2) at x400 magnification, and the mean vascularity recorded for five fields for each specimen. RESULTS: Mean vascular counts were as follows: normal skin 5.9, common acquired nevus 9.1, nevus with features of DMN 10.3, DMN, slight atypia 11.8; DMN, moderate atypia 12.2; DMN, severe atypia 14.8; primary CMM 25.4; and metastatic melanoma 29.5). Significant differences were recorded for DMN, severe atypia versus melanoma (p less than 0.01), DMN, severe versus common nevi (p less than 0.02) and versus nevi with features of DMN (P less than 0.05). When microvessel counts from CMM in the radial growth phase were compared with those from CMM in the vertical growth phase, or CMM less than 1.0 mm versus those greater than 1.0 mm, no significant differences were found. However, CMM in radial growth did differ from severely atypical DMN (22.4 versus 14.8, p less than 0.05). CONCLUSIONS: These results quantify for the first time a gradual rise in vascularity with tumor progression in the melanocytic system and onset of angiogenesis during the radial growth phase of CMM. Other than severely atypical DMN, DMN did not differ substantially from common nevi with reference to overall vascularity.     

Differential permeability of lymphatic and blood vessels in determining the route of metastasis as demonstrated by indirect lymphography

Indirect mammo-lymphography with serial radiograms was made on rats bearing three established rat mammary carcinomas (SMT-2A, TMT-50, MT-W9B), with the water-soluble contrast medium, Iotasul. In the lymphogenously metastasizing SMT-2A, fine lymphatic sprouts from the tumor were seen converging into an afferent lymph vessel that was extending toward a metastatic regional lymph node, in 15–30 min. For 45 min, the dye remained localized in the primary tumor with no other vascular structures or viscera visible until it emerged in the urinary bladder, indicating that Iotasul was absorbed slowly into the systemic circulation via lymphatics and diluted beyond recognition by lymph and blood, and then reconcentrated in urine. In contrast, in the hematogenously metastasizing TMT-50, Iotasul was rapidly diffused into the blood stream, revealing the inferior caval vein within 5 min, and by 15 min the heart, aorta, common carotid arteries, kidney and ureter were all clearly revealed. In the non-metastasizing MT-W9B host, several small vascular markings around the tumor were seen by 10 min and the outline of kidneys and urinary bladder in 15 min, suggesting that the dye was also absorbed through blood capillaries but somewhat slowly. Thus, the differential vascular permeability in rat mammary tumors revealed by Iotasul has not only helped to distinguish lymphatics from blood vessels, but also to correlate it with their metastatic potential.     

Tumor lymphangiogenesis predicts melanoma metastasis to sentinel lymph nodes.

Cutaneous melanoma is a common melanocytic neoplasm that can quickly metastasize to regional lymph nodes. Currently, prognosis is determined by measuring tumor thickness but more reliable markers for metastatic spread are urgently needed. We investigated whether the extent of tumor lymphangiogenesis can predict melanoma metastasis to sentinel lymph nodes. We quantified the extent of tumor lymphangiogenesis, as well as other factors, in excised primary tumors and in sentinel lymph node biopsy samples from 45 patients with primary cutaneous melanoma. The results were correlated with histological and clinical outcome. Primary melanomas from patients whose tumors had metastasized to the sentinel lymph nodes contained prominent 'hot spots' of increased lymphatic vessel density, compared to nonmetastatic tumors. Multivariate risk analysis revealed that the lymphatic vascular area of primary melanomas, an index of tumor lymphangiogenesis, was the most sensitive prognostic marker for sentinel lymph node metastasis, and was even able to more accurately predict which tumors were metastatic to sentinel lymph nodes than the currently used method of measuring tumor thickness. Highly lymphangiogenic melanomas maintained their lymphangiogenic activity after metastasis to the sentinel lymph node. The extent of tumor lymphangiogenesis is a highly sensitive (83%) and specific (89%) prognostic marker of lymph node metastasis. Assessment of lymphangiogenesis in primary melanomas may be a more effective approach than the currently used technique of measuring tumor thickness in selecting patients with early metastatic disease for aggressive therapy.     

Mitotic rate in melanoma: a reexamination

We reexamined the relationship between mitotic rate and overall survival in more than 1,200 cases of cutaneous melanoma with long-term follow-up. Like others, we found that mitotic rate was significantly associated with survival (P < 4 x 10(-8)) and more prognostic than tumor ulceration but was not an independent prognosticator because it was significantly associated with tumor thickness and ulceration. Thus, all 3 histologic variables are interrelated; among these, tumor thickness is the most important. Although mitotic rate can be effectively categorized in 3 groups (1/mm2, 1/mm2(-4)/mm2, and > 4/mm2), the optimal way to use mitotic rate remains unclear, and even this simplification requires determining the raw number per square millimeter. Because the collective information provided by tumor thickness, mitotic rate, ulceration, patient age, and site of tumor about hard outcomes such as 5-year fatality is limited and because measuring mitotic rate requires extra time, we recommend that mitotic rate need not be part of routine reports on cutaneous melanoma. Nevertheless, mitotic rate should continued to be measured in academic centers and other sites that maintain large prospective databases on melanoma, and it should be included in further studies of prognosis and adjuvant therapies for cutaneous melanoma.     

Genomic alterations in primary cutaneous melanomas detected by metaphase comparative genomic hybridization with laser capture or manual microdissection: 6p gains may predict poor outcome

To clarify the correlation of genomic alterations with clinical and histological features, we performed metaphase comparative genomic hybridization analysis on 20 primary cutaneous melanomas, which were obtained by laser capture or manual microdissection, and 16 melanoma cell lines. There were no differences in the average number of aberrations between acral melanomas (AM) and non-AM, although gains of 5q and 11q13 were more frequent (P=0.05) and 10q loss was less frequent (P=0.01) in AM than in non-AM. Although tumor thickness is considered a measurable estimate of clinical expression, there were no differences in the average number of aberrations among 4 groups, classified by thickness of the tumor. While the majority of aberrations were equally distributed among the 4 groups, 6p gains were found only in the thickest tumors. Patients with 6p or 1q gains had a lower overall survival rate than those without them (P=0.0002 or P=0.013). While gains of 1q, 2q, 3p, 3q, 7q, 20p, and 20q were more frequent in the cell lines than in the primary tumors (P<0.01), losses of 6q, 9p, 10p, and 10q were equally found in both cell lines and primary tumors. The present study showed that chromosomal aberrations had already occurred in the thinner tumors, and that 6p and 1q gains may be a prognostic factor.     

Tumor lymphangiogenesis: a novel prognostic indicator for cutaneous melanoma metastasis and survival

Malignant melanomas of the skin are distinguished by their propensity for early metastatic spread via lymphatic vessels to regional lymph nodes, and lymph node metastasis is a major determinant for the staging and clinical management of melanoma. However, the importance of tumor-induced lymphangiogenesis for lymphatic melanoma spread has remained unclear. We investigated whether tumor lymphangiogenesis occurs in human malignant melanomas of the skin and whether the extent of tumor lymphangiogenesis may be related to the risk for lymph node metastasis and to patient survival, using double immunostains for the novel lymphatic endothelial marker LYVE-1 and for the panvascular marker CD31. Tumor samples were obtained from clinically and histologically closely matched cases of primary melanomas with early lymph node metastasis (n = 18) and from nonmetastatic melanomas (n = 19). Hot spots of proliferating intratumoral and peritumoral lymphatic vessels were detected in a large number of melanomas. The incidence of intratumoral lymphatics was significantly higher in metastatic melanomas and correlated with poor disease-free survival. Metastatic melanomas had significantly more and larger tumor-associated lymphatic vessels, and a relative lymphatic vessel area of >1.5% was significantly associated with poor disease-free and overall survival. In contrast, no differences in the density of tumor-associated blood vessels were found. Vascular endothelial growth factor and vascular endothelial growth factor-C expression was equally detected in a minority of cases in both groups. Our results reveal tumor lymphangiogenesis as a novel prognostic indicator for the risk of lymph node metastasis in cutaneous melanoma.     

Impact of sentinel lymphadenectomy on survival in a murine model of melanoma

Lymphatic mapping and sentinel lymph node biopsy—also termed sentinel lymphadenectomy (SL)—has become a standard of care for patients with primary invasive cutaneous melanoma. This technique has been shown to provide accurate information about the disease status of the regional lymph node basins at risk for metastasis, provide prognostic information, and provide durable regional lymph node control. The potential survival benefit afforded to patients undergoing SL is controversial. Central to this controversy is whether metastasis to regional lymph nodes occurs independent of or prior to widespread hematogenous dissemination. A related area of uncertainty is whether tumor cells residing within regional lymph nodes have increased metastatic potential. We have used a murine model of primary invasive cutaneous melanoma based on injection of B16-BL6 melanoma cells into the pinna to address two questions: (1) does SL plus wide excision of the primary tumor result in a survival advantage over wide excision alone; and (2) do melanoma cells growing within lymph nodes produce a higher incidence of hematogenous metastases than do cells growing at the primary tumor site? We found that SL significantly improved the survival of mice with small primary tumors. We found no difference in the incidence of lung metastases produced by B16-BL6 melanoma cells growing exclusively within regional lymph nodes and cells growing within the pinna.     

Vascular retardation in dormant growth-stunted malignant melanomas.

Progression and metastatic spread of primary cutaneous melanoma (PCM) is largely predicted by the thickness of the primary tumor. However, the accretive or proliferative pattern of growth of PCM is another aspect that might affect the prognosis. We retrieved from our histopathological files 11 superficial spreading PCM which had been documented to show an almost stable size for at least 3 years before excision. The area of the PCM at the skin surface had been measured by planimetry on the excision specimens. Histological sections were used to measure the maximum thickness of the neoplasms. A PCM volume estimate was derived by multiplying the surface area by the thickness of the tumors. In addition, the vessel area was determined beneath and outside the PCM lateral margins on Ulex europaeus agglutinin-1-stained sections using computer-assisted image analysis. Peritumoral vascularity was significantly more developed than at distance of the neoplasms. A significant negative exponential correlation was yielded between the peritumoral vascularity and the PCM volume estimate. Such vascular eclipse might be the cause of clinical PCM dormancy. However, other possible independent mechanisms are not ruled out by the present study.     

Atypical Spitz nevi/tumors: lack of consensus for diagnosis, discrimination from melanoma, and prediction of outcome.

The biological nature of Spitz nevi/tumors and their diagnostic distinction from, or relationship to, melanoma remain unresolved issues. In this report, a series of 30 melanocytic lesions removed from 28 patients, including atypical Spitz nevi/tumors and metastasizing Spitzoid tumors/melanomas, were evaluated by a panel of dermatopathologists to evaluate interobserver diagnostic concordance and to assess the prognostic power of histological criteria. For inclusion in the study, each lesion had to display some criteria for the Spitz nevus, and in addition one of the following was required: (1) definitive clinical outcome such as metastasis or death of disease, or (2) long-term follow-up if the patient remained disease free. Each lesion was reviewed independently and blinded as to the clinical data by 10 pathologists, who categorized them as (1) typical Spitz nevus/tumor, (2) atypical Spitz nevus/tumor, (3) melanoma, (4) tumor with unknown biological potential, or (5) other melanocytic lesion. There was limited discussion of criteria before the review. Evaluation of 17 Spitzoid lesions yielded no clear consensus as to diagnosis; in only one case did six or more pathologists agree on a single category, regardless of clinical outcome. Notably, however, some lesions that proved fatal were categorized by most observers as either Spitz nevi or atypical Spitz tumors. Conversely, seven or more pathologists scored 13 lesions as melanoma. These results illustrate (1) substantial diagnostic difficulties posed by many Spitz tumors, especially those with atypical features, even among experts, and (2) the lack of objective criteria for their distinction from melanoma and for gauging their malignant potential. Nevertheless, our observations do suggest that a biological relationship exists between the Spitz nevus/tumor and melanoma.