Treatment of unknown primary melanoma

Melanoma of unknown primary

Formally described in the 1960s, melanoma of unknown primary (MUP) is characterized by the finding of metastatic melanoma within the lymph nodes, subcutaneous tissues, and other distant sites without an evident primary lesion. The most likely hypothesis of its etiology is an immune-mediated regression of the primary after metastasis has occurred. In addition, patients with MUP appear to have equivalent or better outcomes compared with patients with known primaries of a similar stage.

Treatment of Regional Metastatic Melanoma of Unknown Primary Origin

(1) Background: The purpose of this retrospective study was to evaluate the recurrence and survival rates of metastatic melanoma of unknown primary origin (MUP), in order to further refine current recommendations for the surgical treatment; (2) Methods: Medical data of all MUP patients registered between 2000 and 2011, were analyzed. Seventy-eight patients were categorized in either lymph node (axilla, groin, head-and neck) or subcutaneous MUP. Axillary node MUPs were generally treated with dissections of levels I-III, inguinal node MUPs with combined superficial and deep groin dissections, and head-and-neck node MUPs with neck dissections to various extents, based on lymph drainage patterns. Subcutaneous lesions were excised with 1–2 cm margins. The primary outcome was treatment outcomes in terms of (loco)regional recurrence and survival rates; (3) Results: Lymph node MUP recurred regionally in 11% of patients, with an overall recurrence rate of 45%. In contrast, subcutaneous MUP recurred locally in 65% of patients with an overall recurrence rate of 78%. This latter group had a significantly shorter disease-free interval than patients with lymph node MUP (p = 0.000). In the entire study population, 5-year and 10-year overall survival rates were 56% and 47% respectively, with no differences observed between the various subgroups; (4) Conclusion: The relatively low regional recurrence rate after regional lymph node dissection (11%) supports its current status as standard surgical treatment for lymph node MUP. Subcutaneous MUP, on the contrary, appears to recur both locally (65%) and overall (78%) at a significantly higher rate, suggesting a different biological behavior. However, wide local excision remains the best available option for this specific group.

Metastatic melanomas of unknown primary show better prognosis than those of known primary: a systematic review and meta-analysis of observational studies

BACKGROUND

Melanoma of unknown primary (MUP) is a condition of metastatic melanoma without a primary lesion.

OBJECTIVE

We sought to identify the prognosis of MUP compared with melanoma of known primary (MKP).

METHODS

We searched for observational studies containing at least 10 patients with MUP from MEDLINE and EMBASE from inception to December 22, 2012. The outcomes of interest were overall and disease-free survival; meta-analyses of hazard ratio stratified by stage using a random effects model were performed. In addition, second systematic review identified risk factors influencing the survival of patients with MUP.

RESULTS

Eighteen studies including 2084 patients with MUP and 5894 with MKP were included. MUP had a better overall survival compared with MKP in stage III (15 studies; hazard ratio 0.83, 95% confidence interval 0.73-0.96, P = .010) and stage IV (6 studies; hazard ratio 0.85, 95% confidence interval 0.75-0.96, P = .008). Secondly, 22 studies including 3312 patients with MUP were reviewed, and increased stage and old age were the risk factors in patients with MUP.

LIMITATIONS

Diverse observational studies were reviewed, and selection and reporting biases are possible.

CONCLUSIONS

The current meta-analyses suggest better survival outcomes in patients with MUP than those in patients with MKP with the same corresponding tumor stage.

Melanoma of unknown primary site: a 33-year experience at the Turin Melanoma Centre

Unknown melanoma occurs as metastasis to skin, nodes or viscera, without a detectable cutaneous primary tumour. We reviewed our database of 4881 melanoma patients, diagnosed and followed up prospectively for a 33-year period. We identified 93 cases of metastatic melanoma without evidence of primary; however, five of these patients had a history of a previous excision of a presumed benign lesion without histological examination and were excluded from analyses. At diagnosis, metastases were cutaneous in 35.3% of cases, nodal in 43.2% and visceral in 17% of cases; in 4.5% of patients, both skin and nodes were involved. In all cases, clinical inspection and staging procedures performed at diagnosis of metastatic disease failed to identify a primary melanoma. In 11 cases (11.8%), extensively regressed pigmented lesions (without evidence of melanoma cells at the histological examination) were documented; moreover, we identified in our series five patients with unknown primary affected by vitiligo. The 5-year and 10-year overall survival rates were 49.6 and 41.4%, respectively, with a median of 4.9 years. The 5-year and 10-year time to progression rates were 39.4 and 32.3%, respectively, with a median of 2.3 years. Survival was longer in females and showed significant differences among patients with skin, lymph node or visceral involvement at diagnosis. In melanoma patients, unknown primary represents a not so rare event, with an uncertain origin. We confirmed the relatively good prognosis of unknown primary melanoma patients, a fact that has to be taken into consideration for their management.

Malignant melanoma of unknown primary site. To make the long story short. A systematic review of the literature

INTRODUCTION

Although more than 90% of melanomas have a cutaneous origin, occasionally it is discovered as a secondary deposit without evident primary site. The aim of this study was to systematically review published literature and analyse data on incidence, presentation, therapeutic interventions, survival and prognostic factors.

METHODS

We searched MEDLINE, (search terms Melanom*, unknown origin, unknown primary, indolent, occult) and the abstracts from major congresses of the last 4 years and perused the references of the retrieved relevant articles.

RESULTS

4348 patients with MUP were reported along with 132,643 patients with Melanoma of Known Primary (MKP). The incidence of MUP was 3.2%. The male to female ratio was 2:1 while the age peak was in the 4th and 5th decades. MUP patients harbouring nodal disease had a median overall survival ranging between 24 and 127 months, 5-year survival rate between 28.6% and 75.6% and 10-year survival rate between 18.8% and 62.9%. MUP patients with visceral disease had median survival times between 3 and 16 months, and 5-year survival rates between 5.9% and 18%. Presence of tumour regression in metastatic sites and low nodal burden were associated with favourable outcome. Potentially curative surgical treatment offered survival advantage in comparison to patients with residual metastatic foci. MUP patients who received adjuvant chemotherapy or radiotherapy paradoxically seemed to fare worse compared to patients observed.

CONCLUSIONS

This is the first review to bring together the information of 89 years and to analyze all the potential information accumulated. Although a well know entity no consensus is reached in order to describe MUP presentation, management or prognosis.

Melanin-targeted preclinical PET imaging of melanoma metastasis

Dialkylamino-alkyl-benzamides possess an affinity for melanin, suggesting that labeling of such benzamides with (18)F could potentially produce melanin-targeted PET probes able to identify melanotic melanoma metastases in vivo with high sensitivity and specificity.

METHODS

In this study, N-[2-(diethylamino)ethyl]-4-(18)F-fluorobenzamide ((18)F-FBZA) was synthesized via a 1-step conjugation reaction. The sigma-receptor binding affinity of (19)F-FBZA was determined along with the in vitro cellular uptake of radiofluorinated (18)F-FBZA in B16F10 cells. In vivo distribution and small-animal PET studies were conducted on mice bearing B16F10 melanoma, A375M amelanotic melanoma, and U87MG tumors, and comparative studies were performed with (18)F-FDG PET in the melanoma models.

RESULTS

In vitro, uptake of (18)F-FBZA was significantly higher in B16F10 cells treated with l-tyrosine (P < 0.001). In vivo, (18)F-FBZA displayed significant tumor uptake; at 2 h, 5.94 +/- 1.83 percentage injected dose (%ID) per gram was observed in B16F10 tumors and only 0.75 +/- 0.09 %ID/g and 0.56 +/- 0.13 %ID/g was observed in amelanotic A375M and U87MG tumors, respectively. Lung uptake was significantly higher in murine lungs bearing melanotic B16F10 pulmonary metastases than in normal murine lungs (P < 0.01). Small-animal PET clearly identified melanotic lesions in both primary and pulmonary metastasis B16F10 tumor models. Coregistered micro-CT with small-animal PET along with biopsies further confirmed the presence of tumor lesions in the mouse lungs.

CONCLUSION

(18)F-FBZA specifically targets primary and metastatic melanotic melanoma lesions with high tumor uptake and may have translational potential.

Improved survival for stage IV melanoma from an unknown primary site

PURPOSE We previously demonstrated a survival advantage for nodal metastasis of melanoma from an unknown primary (MUP) versus melanoma from a known primary (MKP). We hypothesized that this survival benefit would extend to MUP patients with distant (stage IV) metastasis. PATIENTS AND METHODS We reviewed prospectively acquired data for 2,247 patients diagnosed with American Joint Committee on Cancer stage IV melanoma at our cancer center between 1971 and 2005. Cox regression analysis in a multivariate model identified prognostic factors significant for survival. MUP and MKP patients were then matched by significant covariates. Overall survival (OS) was estimated by Kaplan-Meier method and compared by log-rank analysis. Results There were 1,849 MKP and 398 MUP patients. Multivariate analysis of patients with complete data sets identified known/unknown primary (hazard ratio [HR], 1.141; P = .032) and five other significant covariates: age (HR, 1.148; P = .007), sex (HR, 1.17; P = .001), site of metastasis (HR, 1.336; P < .001), number of different metastatic sites (HR, 1.303; P < .001), and decade of diagnosis (HR, 0.713; P < .001). Prognostic matching yielded 392 MUP-MKP pairs. Median OS and 5-year OS rate were significantly greater (P < .001) for MUP patients than for all matched MKP patients or for MKP patients matched by M1 category (for M1b and M1c) or number of metastatic sites. CONCLUSION The survival advantage previously reported for patients with stage III MUP also applies to patients with stage IV MUP. The mechanism responsible for this improved survival may provide clues for more effective treatment of stage IV melanoma and therefore warrants further investigation. The improved results for MUP suggest that these patients deserve aggressive therapy.

Diffuse liver infiltration by melanoma of unknown primary origin: one case report and literature review

Diffuse liver infiltration by melanoma of unknown primary origin is rare. We encountered a unique case of diffuse liver infiltration by melanoma of unknown primary origin in our hospital. A 62-year-old woman was referred to our hospital for anorexia of 6 months duration and abdominal distension for 1 month. Ultrasonography (US), computerized tomography (CT) and magnetic resonance imaging (MRI) revealed an obvious enlarged liver without detectable nodules. She was diagnosed as liver metastasis by melanoma of unknown primary origin via percutaneous liver biopsy. The report demonstrates the difficulty of making a noninvasive diagnosis of diffuse hepatic infiltration on metastatic melanoma.

Radiculopathy due to malignant melanoma in the sacrum with unknown primary site

Melanoma is an interesting tumor, showing the appearance of metastasis without any trace of its primary lesion. To report a very rare case of malignant melanoma in the sacrum with unknown primary origin. The authors present a case of a 52-year-old man who was admitted with increasing lower back, left buttock, and left lower extremity pain, and dysuria. Plain radiograph, computed tomography scan, and magnetic resonance imaging revealed a destructive lesion in the sacrum and left ilium, which infiltrated the spinal canal and sacroiliac joint. The tumor cells were immunoreactive for HMB-45. The pathological diagnosis was malignant melanoma. No obvious primary malignant melanoma was detected on the skin surface, on the oral or anal mucosa, or in the fundus oculi. Following radiotherapy and chemotherapy, the severe buttock pain disappeared and the patient was able to walk without impediment. However the patient died nine months after initial diagnosis. Malignant melanoma in the sacrum with an unknown primary site, showing S1 radiculopathy is reported for the first time. The melanoma could have been a metastatic tumor of the sacrum, although the primary site was not detected. The incidence of primary melanoma is increasing faster than any other cancer. Thus treatment of patients with spinal metastasis of melanoma is an important challenge for orthopedic surgeons.

Completely regressed primary cutaneous malignant melanoma with nodal and/or visceral metastases: a report of 5 cases and assessment of the literature and diagnostic criteria

BACKGROUND

Partial regression of primary cutaneous malignant melanoma is not uncommon and may predict a higher likelihood of metastasis and decreased survival. Complete histologic regression of a primary cutaneous melanoma is a rarer occurrence, with only 34 cases reported in the English-language or English language-summarized literature.

OBSERVATION

We detail 4 cases of complete histologic regression of primary cutaneous melanoma, discovered at presentation with metastatic disease. A pigmented lesion or its remnant, coupled with historical information, was strongly suggestive of cutaneous melanoma. Histologic examination of the lesions, using multiple levels and immunohistochemical stains, failed to reveal residual melanoma. Our cases are typified by the presence of metastasis of melanoma to regional lymph nodes, with the absence of other suspect skin lesions or malignancies. In addition, we present a fifth case involving a completely regressed lesion on the scalp in a patient with cerebral melanoma metastasis and comment on the implications of this case to accepted diagnostic criteria, proposing that consideration of modification to the criteria be entertained.

CONCLUSION

The concept of completely regressed primary cutaneous melanoma is reviewed and the literature critically appraised. When one considers a diagnosis of completely regressed primary cutaneous melanoma, cases must be well documented and biopsy proven. Patients with metastatic melanoma and an occult primary lesion require a thorough skin examination, with serious consideration given to the possibility of completely regressed cutaneous melanoma.

Possible role of dermoscopy in the detection of a primary cutaneous melanoma of unknown origin

For 2-8% of patients with metastatic melanoma, cutaneous and mucosal clinical examination does not lead to diagnosis of the primary tumour, which remains unknown. We report the case of a 41-year-old male patient who had received a diagnosis of metastatic melanoma after histological examination of an enlarged axillary lymph node, without previous detection of the primary lesion at his first dermatological examination. No pigmented skin lesions located in the anatomical area potentially drained by the affected axillary basin showed clinical features suggestive of a melanoma. Neither did the so-called 'ugly duckling' sign help us to identify the melanoma, because of the presence of a large number of clinically similar, common or slightly atypical melanocytic lesions located in that area. After dermoscopic examination we were able to narrow the field of possible candidates for excision to four lesions, selected on the basis of their dermoscopic features. Histological examination revealed the primary melanoma (superficial spreading melanoma (SSM), level III, thickness 0.5 mm)--located on the back--and three naevi with atypia. Preoperative distinction of the melanoma from the other three lesions was not possible because of the lack of well-established features of malignancy, even at dermoscopic analysis ('featureless' melanoma). Dermoscopy may thus play a role in the detection of a clinically unknown primary melanoma by narrowing the field of lesions to be removed for histological examination, saving many unnecessary excisions that would otherwise be inevitable.

Metastatic melanoma to lymph nodes in patients with unknown primary sites

BACKGROUND

The natural history of metastatic melanoma in lymph nodes in the absence of a known primary site (MUP) has been defined poorly; thus, treatment guidelines for patients with MUP are not clear-cut.

METHODS

The authors conducted a retrospective analysis of consecutive patients with melanoma (from 1990 to 2001) who underwent surgical resection for melanoma metastatic to regional lymph nodes. Among those patients, 71 patients with MUP and 466 control patients who had regional lymph node metastases of similar stage with a known primary site were identified. Associations between clinicopathologic factors and survival were estimated by using the Cox proportional hazards model.

RESULTS

After they underwent lymph node dissection, patients with MUP were classified with N1b disease (47%), N2b disease (14%), or N3 disease (39%). With a median follow-up of 7.7 years, the 5-year and 10-year overall survival rates were 55% and 44%, respectively, for patients with MUP, compared with 42% and 32%, respectively, for the control group (P = .04). In multivariate analyses, age 50 years or older, male gender, and N2b or N3 disease status were identified as adverse prognostic factors, and MUP was identified as a favorable prognostic factor (hazard ratio, 0.61; 95% confidence interval, 0.42-0.86; P = .006) for overall survival.

CONCLUSIONS

The relatively favorable long-term survival of patients with MUP in the current study suggested that patients with MUP have a natural history that is similar to (if not better than) the survival of many patients with Stage III disease. Therefore, patients with MUP should be treated with an aggressive surgical approach with curative intent and should be considered for Stage III adjuvant therapy protocols. Cancer 2006. (c) 2006 American Cancer Society.

Bilateral oncocytic malignant melanoma in axillary lymph nodes without evidence of an extranodal primary

A malignant melanoma was diagnosed in an axillary lymph node of a 49-year-old man. The tumor was examined by electron microscopy and was found to be composed of large oncocytic cells, filled with abundant mitochondria. No primary tumor could be identified on the skin or within internal organs. Approximately 2 years after the initial diagnosis, the patient presented with malignant melanoma in an axillary lymph node on the contralateral side. The second tumor also expressed the same oncocytic phenotype, favoring the common origin of both tumors. These data illustrate that oncocytic melanomas may retain their oncocytic phenotype during metastatic dissemination.

Metastatic melanoma of unknown primary origin shows prognostic similarities to regional metastatic melanoma: recommendations for initial staging examinations

BACKGROUND

Metastatic melanoma of unknown primary origin accounts for approximately 2-6% of all melanoma cases. The prognostic significance of this diagnosis is still controversial.

METHODS

Of 3258 patients with malignant melanoma recorded during the period 1976-1996, 2.3% had metastases of unknown primary origin. Anatomic distribution, clinical stage, and survival probabilities were evaluated.

RESULTS

Thirty patients were classified as having cutaneous or subcutaneous in-transit metastases, and they showed a 5-year survival rate of 83%. Thirty-seven patients were classified as having lymph node metastasis, and their 5-year survival rate was 50%. Disseminated disease was diagnosed in only 8 patients, who had a median survival of 6 months. Comparison of survival probabilities for patients with in-transit metastases and unknown primary tumors with the probabilities for those with cutaneous primary tumors revealed a significant advantage for the former group. No significant differences were found for patients with lymph node metastasis when those with unknown primary tumors were compared with those who had cutaneous melanomas with regional lymph node metastasis.

CONCLUSIONS

The clinical disease course of patients with metastatic melanoma of unknown primary origin is similar to that of patients with primary cutaneous melanoma when the same clinical stages of the disease are compared. Based on the assumption that the majority of regional metastases develop from completely regressed primary cutaneous melanoma, recommendations for initial staging examinations in patients with unknown primary tumors are given in this article.

Melanoma of unknown primary site: presentation, treatment, and prognosis--a single institution study. University of Pennsylvania Pigmented Lesion Study Group

BACKGROUND

A retrospective analysis of 40 patients diagnosed with melanoma of unknown primary site (MUP) was undertaken to analyze the etiology and clinical behavior of this presentation.

METHODS

The patient records were located by a computer search of the Pigmented Lesion Clinic data base at the University of Pennsylvania. With the Cox proportional hazards model, the survival of the MUP patients with lymph node presentation was compared with that of patients with lymph node disease and a known concurrent primary melanoma.

RESULTS

Sixty-five percent of the patients presented with lymph node metastasis only, 28% presented with visceral lesions, and 8% presented with subcutaneous nodules. The prevalence of dysplastic nevi was 22.5%. The overall 4-year survival rate for the 40 MUP patients was 55% +/- 9%. The 4-year survival (57% +/- 12%) of patients with lymph node presentation was compared with that of patients presenting with lymph node disease and a known concurrent primary melanoma (19 +/- 6%). Survival was significantly different between the groups (P = 0.008). This survival difference remained significant (P = 0.02) even after adjustments for number of positive lymph nodes, year of diagnosis, and age at diagnosis.

CONCLUSIONS

This analysis revealed that MUP patients with lymph node metastasis survived significantly longer than patients diagnosed with lymph node metastasis concurrent with a known cutaneous primary melanoma. The prevalence of dysplastic nevi in the MUP patient series was intermediate between that reported among primary melanoma patients and that reported among population controls, suggesting the likelihood of a primary cutaneous origin for the metastatic melanoma.

Therapeutic lymphadenectomy in melanomas of the head and neck

This retrospective study describes patients with loco-regionally metastasized melanoma of the head and neck. All patients underwent a therapeutic lymph node dissection. The 3-year survival rate was 35%. Duration of disease-free interval, number of lymph nodes involved, and extent of neck dissection proved of no influence on survival rates. Locoregional recurrence occurred in 10 patients and always proved to be a sign of systemic dissemination. Ultimately, 19 patients developed systemic disease. More than 40% developed cerebral metastases and the cerebrum was the second most involved site. As cerebral involvement occurs often in head and neck melanoma, a computed tomography or magnetic resonance imaging scan of the brain is recommended in the routine work-up before lymph node dissection. Furthermore, because the extent of the surgical procedure had no influence on local recurrence rate and overall survival, a selective approach, preserving functional structures, is advocated.