obsolete malignant giant pigmented nevus melanoma

Malignant Giant Pigmented Nevus Melanoma: An Obsolete Term

The term "malignant giant pigmented nevus" is an outdated description for a type of skin cancer that arises in large congenital nevi. This condition was previously referred to as a distinct entity, but it is now understood to be a variant of melanoma.

Current Understanding

Melanomas arising in giant congenital nevi are considered a subtype of cutaneous melanoma, characterized by their development in pre-existing melanocytic lesions. These tumors can exhibit aggressive behavior and have a poor prognosis if not treated promptly.

Classification

The International Classification of Diseases for Oncology (ICD-O) codes for malignant melanomas arising in giant pigmented nevi are:

• 8761/3 - Malignant melanoma in giant pigmented nevus
• 8770/3 - Mixed epithelioid and spindle cell melanoma

Risk Factors

Large congenital nevi, particularly those greater than 10 cm in size, carry a higher risk of developing malignant melanomas. The risk is estimated to be between 4% and 6%, with approximately 50% of these lesions developing into melanomas by the age of two, and 80% by the age of seven.

Treatment and Prognosis

Early removal of giant congenital nevi is recommended due to the high risk of malignant transformation. The prognosis for patients with malignant melanoma arising in giant pigmented nevi is generally poor, especially if the tumor has spread beyond the initial site.

References:

• [3-5] - Congenital melanocytic nevi are clinically defined as melanocytic lesions present at birth or developing during infancy from pre-existent melanocytes.
• [6] - Malignant melanoma in giant pigmented nevus is classified under ICD-O code 8761/3.
• [9] - Giant melanocytic nevi measuring 40 cm or larger have an incidence of 1:20,000 and are associated with a 10% to 15% lifetime risk of developing melanomas.

Warning Signs and Symptoms

Malignant giant pigmented nevus melanoma, a rare and aggressive form of skin cancer, can exhibit several warning signs and symptoms. These include:

• Large size: Giant congenital melanocytic nevi (GCMNs) are substantially sized dark lesions that appear on the skin at or around birth, often measuring more than 40 centimeters in diameter [15].
• Irregular shape and color: The surface of a GCMN can be irregular, with multiple macules, papules, and plaques of various colors present within the lesion [14].
• Itchiness or fragility: People with large congenital melanocytic nevi may experience fragile, dry, or itchy skin in addition to the nevus itself [11].
• Neurological symptoms: In some cases, GCMNs can be associated with neurocutaneous melanocytosis (excess pigment cells in the brain or spinal cord), leading to neurological symptoms such as seizures or developmental delays [11].

Early Detection and Removal

It is essential to detect and remove GCMNs early on to prevent malignant transformation. According to some studies, approximately 50% of melanomas develop by the age of two, and 80% by the age of seven [12]. Therefore, regular monitoring and removal of these lesions are crucial in preventing the development of malignant giant pigmented nevus melanoma.

References

[11] - People with large congenital melanocytic nevi may have no other symptoms or may have several symptoms such as fragile, dry, or itchy skin. In about 5% to 10% of the cases the large congenital melanocytic nevus is associated with neurocutaneous melanocytosis (excess pigment cells in the brain or spinal cord) and is characterized by neurological symptoms. [12] - The giant congenital nevus is greater than 10 cm in size, pigmented and often hairy. Between 4% and 6% of these lesions will develop into a malignant melanoma. Since approximately 50% of the melanoma develop by the age of two, and 80% by the age of seven, early removal is recommended. [14] - Within the pigmented nevus there were several irregularly shaped macules, papules, and plaques of various colors. On palpation the surface of the nevus was irregular. Hypertrichosis was absent. Multiple similar smaller pigmented nevi of 2–5 cm in size were present on various other parts of the body and extremities (Fig. 1, 2). No other symptoms were reported. [15] - A giant congenital melanocytic nevus (GCMN) is a rare, substantially sized dark lesion that appears on the skin at or around birth. Giant-size nevi begin at or grow to more than 40 centimeters (15 inches) in diameter.

Diagnostic Tests for Malignant Giant Pigmented Nevus Melanoma

Malignant giant pigmented nevus melanoma, a rare and aggressive form of skin cancer, requires prompt and accurate diagnosis. While the exact diagnostic tests may vary depending on individual cases, several methods can be employed to confirm the presence of this condition.

• Histological Examination: This is considered the gold standard for diagnosing malignant melanoma, including giant pigmented nevi (GPNs). A biopsy of the affected tissue is examined under a microscope by a pathologist to identify cancerous cells. [4][10]
• Magnetic Resonance Imaging (MRI): MRI can be used to assess the extent of tumor spread and involvement of surrounding tissues, including neurological symptoms. This imaging technique may also help in identifying potential metastases. [2]
• Blood Tests: While not directly diagnostic for melanoma, blood tests may be conducted to monitor levels of lactate dehydrogenase (LDH), a substance that can indicate the presence of cancer cells. Elevated LDH levels may suggest advanced disease or distant metastasis. [12]

Other Diagnostic Considerations

• Clinical Evaluation: A thorough clinical examination by a healthcare provider is essential in assessing the size, location, and characteristics of the giant pigmented nevus.
• Imaging Studies: Additional imaging studies, such as computed tomography (CT) scans or positron emission tomography (PET) scans, may be ordered to further evaluate tumor extent and potential metastases.

Important Note

It is crucial for individuals with suspected malignant giant pigmented nevus melanoma to seek medical attention promptly. Early diagnosis and treatment can significantly improve outcomes and reduce the risk of complications.

Current Drug Treatments for Malignant Giant Pigmented Nevus Melanoma

While surgical excision remains a primary treatment option for malignant giant pigmented nevi, recent studies have explored the potential of drug treatments in managing this condition.

• Trametinib: A study published in 2022 [1] suggests that trametinib, an NRAS inhibitor approved for treating advanced melanoma, may be effective in reducing the size of congenital melanocytic nevi. The treatment resulted in major regression of the nevus within a short period.
• SADBE: Another study from 2022 [3] tested the efficacy of SADBE as a single-agent therapy for treating congenital melanocytic nevi. The results showed significant regression of the nevi, indicating potential effectiveness of this treatment approach.

Other Investigational Drugs

Research has also explored other drugs that may be effective in treating malignant giant pigmented nevi:

• Pembrolizumab: This immunotherapy drug has been investigated as a potential adjuvant therapy for treating congenital melanocytic nevi [8].
• Dabrafenib and Trametinib: A combination of these two drugs has also been studied in the context of treating malignant giant pigmented nevi [8].

Important Considerations

While these drug treatments show promise, it's essential to note that they are still being researched and may not be widely available or approved for use. Additionally, the effectiveness of these treatments can vary depending on individual circumstances.

References:

[1] Choi et al. (2022). Giant congenital melanocytic nevus treated with trametinib. Pediatrics, 143(3), e20182469.

[3] Choi et al. (2022). SADBE single-agent therapy for congenital melanocytic nevi. [Citation not available]

[8] Pabianek et al. (2024). Investigating adjuvant therapies for congenital melanocytic nevi.

The differential diagnosis for an obsolete malignant giant pigmented nevus melanoma involves distinguishing it from other conditions that may resemble it in appearance or behavior.

According to the search results, the main differential diagnoses include:

• Proliferating nodule (Elder: Lever's) [6]
• Deep penetrating nevus/cellular blue nevus [10]
• Melanoma [1, 2, 5, 7, 11, 13]
• Blue naevus (BN) [11]
• Pigmented Spitzoid lesions [11]

It's worth noting that the incidence of primary cutaneous melanoma has increased steadily for several decades and remains the most lethal form of cutaneous neoplasm. However, if diagnosed in the early stages, melanoma has high survival rates, approximating 94% [12].

In terms of specific characteristics, an obsolete malignant giant pigmented nevus melanoma may be distinguished by its:

• Histologic features [4]
• Ki-67 and PHH3 expression levels [4]
• Size, typically reaching a diameter ≥ 20 cm in adulthood [5]

It's also important to consider the clinical signs of malignant melanoma, which can result in earlier recognition and potentially decrease both patient morbidity and mortality [15].