Metastatic melanoma with unknown primary

What is it metastatic melanoma with stranger primary?

Metastatic melanoma with unknown primary (MUP) refers to metastatic melanoma in lymph nodes, subcutaneous fabric, or visceral sites in the absence of a detectable primary tumor despite detailed examination [1]. Metastatic melanoma should be considered in the differential diagnosis For any patient presenting with malignancy of unknown origin.

Melanoma commonly metastasizes to regional lymph nodes, liver, lungs, bones, or brain, spreading through lymphatic and hematogenous routes. also can metastasis to the skin, locally or to distant sites [2].

For classification purposes, MUP can be separated into subcutaneous, nodaland visceral disease, with nodal MUP being the most common.

See more images of metastatic melanoma.

Who gets metastatic melanoma with unknown primary?

MUP accounts for approximately 2–9% of metastatic melanoma cases [3]. The average age of patients presenting with MUP is in the fifth and sixth decades of life. [4]. It occurs more commonly in men than in women. This sex The difference is currently inexplicable.

What causes metastatic melanoma with unknown primary?

The origin of MUP is not fully understood. Some possible explanations are included below.

• Tumor cells at the primary site regressed due to tumor infiltration activity lymphocytes. Regression in melanoma is well documented, with a frequency of up to 10%.
• The primary cutaneous The melanoma may have been removed or otherwise destroyed without proper pathologic analysis.
• Primary melanoma was incorrectly interpreted as a benign nevus based on clinical and/or pathological characteristics.
• Evil one transformation of ectopic melanocytes in lymph nodes or other organs may have occurred de novo [1,5].

Genotyping of MUP shows a mutational pattern similar to cutaneous melanoma and not the pattern seen in primary melanoma arising at other sites, such as the mucous membrane or central nervous system. MUP mutations include mutations in the BRAF (particularly the V600E subtype) and NRAS genes [6]. This supports the theory that MUP represents metastasis from an original primary cutaneous melanoma that may or may not have regressed.

What are the clinical characteristics of melanoma with unknown primary?

As the primary site of melanoma is unknown, the presentation of MUP is atypical, in the sense that there is no clinically apparent primary skin disease injury.

Rarely, primary melanoma is found later in a extracutaneous place, as in the eye, or in a sinonasal, vulvovaginalor gastrointestinal area. In most cases, the primary melanoma cannot be found [6].

The most common clinical presentation of MUP is lymph node disease without clinical or radiological evidence of visceral involvement. Lymph node metastases typically appear in the axillary nodes (50%), neck (26%), and groin (20%) [1].

In cases of spread of MUP to visceral sites, the initial symptoms are site-specific.

• Hepatic melanoma can present with hepatomegaly, jaundice, or an abdominal mass.
• Pulmonary melanoma may include a lung lesion or pleural effusion.

Advanced MUP that has spread to distant sites may also present systemic features related to cytokine production, like fever, weight loss and anemia [7].

How is metastatic melanoma with unknown primary diagnosed?

The diagnosis of MUP is generally made based on clinical signs and symptoms consistent with metastatic disease, along with histopathology of a tissue sample confirming the presence of malignant melanocytes, such as excision biopsy from lymph node or needle core biopsy of a solid Organ metastasis [8].

the histological Characteristics of MUP in a tissue sample include:

• The presence of coffee pigment melanin – this is not present in amelanotic melanoma
• Positive melanocytic immunohistochemical markers, such as S100, Melan-A, HMB-45, and SOX10 (SOX10 has been shown to be a reliable marker for identifying metastatic melanoma) [8,9].

It is currently not possible to predict the primary site of MUP from histology, immunohistochemistryor genetics [8].

The requirement for an extensive physical examination to look for the primary injury has been questioned. Exams such as ophthalmoscopy (eye examination with an ophthalmoscope), otoscopy (ear examination with an otoscope), rhinopharyngoscopy (nasal endoscopy and examination of the upper airways), laryngoscopy (examination of the inside of the larynx), sigmoidoscopy (rectal examination) and, in women, gynecological examination, have been traditionally performed, but the yield in searching for a primary lesion is not high. These exams can be expensive, long, and uncomfortable for patients. Special physical examinations are performed using clinical judgment in individual cases. [4].

Other investigations recommended for MUP include Connecticut Images of the head, neck, brain (preferably by Magnetic resonance), thorax, abdomen and pelvis to detect any visceral involvement. CONNECTICUT-PET Scanning can also help stage the disease.

What is the treatment for metastatic melanoma with unknown primary?

Staging

Studies have shown that lymph nodes and subcutaneous MUP have better forecast than stage III melanoma from a known primary site. The American Joint Committee on Cancer (AJCC) recommends:

• MUP occurring in regional lymph nodes should be classified as stage III rather than stage IV disease
• MUP occurring in visceral sites should be classified as stage IV [1,3].

Treatment

For nodal MUP, a radical dissection of the lymph nodes in the affected region is usually performed. Patients who undergo surgery are less likely to have a reappearance of malignant neoplasia and have improved survival compared to patients receiving other treatments. Some patients with stage III MUP may benefit from assistant systemic and radiotherapy with identical criteria to patients with a known primary melanoma when undergoing the same treatment [1,10].

Subcutaneous MUP behaves more like a thick primary melanoma and is usually treated with extensive local treatment excision and sentinel lymph node biopsy, if indicated. A epidermal The component is sometimes identified in the wide local excision specimen, establishing it as primary cutaneous melanoma rather than MUP [10].

A complete metastatic evaluation is performed for MUP developing at a visceral site, including cross-sectional imaging. Management involves resection of any isolated injury when possible.

While adjuvant therapy has an established role in stage III MUP, its role is unclear in stage IV MUP [10].

What is the outcome for metastatic melanoma of unknown primary?

Results from studies comparing MUP patients with matched groups of cutaneous melanoma patients have shown that MUP has similar or better overall survival rates than cutaneous melanoma.

A 2015 systematic review and meta-analysis by Bae et al showed that compared with melanoma of known primary, MUP has better overall survival, with a hazard ratio of 0.83 for stage III disease and a risk of 0.85 for stage IV disease [11].

Favorable forecast factors include:

• Low number of lymph nodes involved
• Female gender
• Absence of visceral metastases (stage IV disease)
• Bass serum lactate dehydrogenase (LDH) in people with stage IV disease
• Early surgical intervention [8,12].

Patients with MUP may have improved survival because there may be a more active tumor-directed immune response against malignant cells (supporting the idea that MUP may be a result of tumor regression) than in primary melanoma. known [13].