ATYPICAL NAEVUS / DYSPLASTIC NAEVUS
MELTUMP
SAMPUS
IAMPUS
AIMP
ATYPICAL SPITZOIDE TUMOR
STUMP
MELANOCYTOMA
Pigmented skin lesionsThey can be benign or malignant . There are also abnormalities in between , uncertain cases where neither the dermatologist nor the pathologist can say with certainty whether it is a benign mole (nevus) or a malignant melanoma . These uncertain cases are also called atypical melanocytic lesions , but many other names are used, which are discussed in this brochure.
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| mole (nevus) |
atypical mole |
melanoma |
Typically, suspicious-looking skin lesions are removed in their entirety ( excision ) and sent to the pathology laboratory. The pathologist examines the tissue under a microscope and makes a diagnosis (what it is) and whether it is malignant.
This diagnosis determines the course of action. If it is a benign mole, no further action is required. If it is a melanoma, the lesion will require further surgery ( re-excision ). The area where the mole was is then excised more widely, with a safety margin of usually 1 cm around the scar. Sometimes the pathologist will determine that there are some malignant features, but not enough to label it a melanoma, and the lesion is completely removed. In that case, no further action is required. And sometimes the pathologist will determine that the lesion, with malignant features but not a melanoma, is not completely removed. In such cases, further surgery is usually recommended to ensure complete removal of the lesion, but not with a 1 cm margin around it, but much narrower, for example, a few millimeters, or even 5 mm.
The final recommendation regarding surgery and follow-up depends on the tumor type and the pathologist's assessment. This advice is laid down in guidelines. There are Dutch, European, and international guidelines, and they are not all identical. Guidelines also change over the years, becoming more flexible or stricter.ATYPICAL NAEVUS / DYSPLASTIC NAEVUSA common mole is called a nevus (naevus naevocellularis). Moles that are suspicious can be assessed by a dermatologist or a general practitioner. The clinical picture, its appearance, determines whether the mole is suspicious. The dermatologist examines its size, any growth, color, whether it has multiple colors or unusual shapes, and its symmetry. The dermatologist usually uses a dermatoscope, a powerful magnifying glass with special lighting.
The diagnosis may be made that it is a common mole with no unusual signs. In that case, no further action is needed. Alternatively, the diagnosis may be made that it appears to be not a common mole, but an abnormal mole (medical term: atypical nevus ), or perhaps even a melanoma . In that case, the entire mole is usually removed and sent to a pathologist.
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| atypical nevus |
atypical nevus |
atypical nevus |
The pathologist's assessment is sometimes available within a few days, but it can also take weeks, especially if the procedure is complex and requires numerous additional stains.
Several outcomes are then possible:
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It's a common mole. |
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It's a melanoma. |
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It's a dysplastic nevus : not a typical mole, nor a melanoma, but something in between. Some atypical features are visible, including irregular cells, but not severe enough to be considered a melanoma. |
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The place is completely out of it. |
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The spot reaches locally to one of the edges or to the bottom, but is not completely gone. |
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It's something completely different. |
A dysplastic nevus ( atypical nevus ) could eventually develop into a melanoma . Therefore, the advice is to remove the nevus in its entirety. So, if the pathologist notes that the spot extends to one of the edges or the base, another surgery will be necessary, either wider or deeper.
Some people with many atypical moles have an increased risk of developing melanoma. Often, they also have family members with many atypical moles, or with one or more melanomas. This may be a hereditary condition called dysplastic nevus syndrome . Other names include FAMMM syndrome (Familial Atypical Multiple Mole/Melanoma syndrome), or familial melanoma . If familial melanoma is suspected, DNA diagnostics can be performed.
Instead of dysplastic nevus, the pathologist may also make other diagnoses, such as MELTUMP , SAMPUS , IAMPUS , AIMP , atypical Spitzoid tumor , STUMP , or melanocytoma . The term melanocytoma is relatively new. In 2018, the WHO proposed using this term for all intermediate forms between a mole and melanoma. However, all other terms are still in use.MELTUMPMELTUMPis an abbreviation for melanocytic tumor of uncertain malignant potential . Melanocytic means that the abnormality, like all other abnormalities discussed in this brochure, is made up of pigment cells ( melanocytes ). Tumor means lump or swelling. The term tumor does not mean that it is malignant. There are benign tumors and malignant tumors. Pigmented skin abnormalities are not always a lump or swelling; they can also be just a pigmented spot that is not raised. Uncertain malignant potential means that it could be a malignant tumor (a melanoma). The pathologist is then unsure whether it is benign or malignant. MELTUMP is an English term; the Dutch name is melanocytic tumor with uncertain biological behavior .WHAT CAUSES A MELTUMP?The cause of a MELTUMP is unknown. A MELTUMP can develop anywhere on the skin. While anyone can develop a MELTUMP, they are more common in people with fair skin.WHAT DOES A MELTUMP LOOK LIKE?A MELTUMP usually appears as a brown or black bump or spot. It actually looks like a mole. A MELTUMP diagnosis can never be made based on the appearance of the spot. The diagnosis can only be made retrospectively by a pathologist, if the spot was removed and submitted for pathological examination. This can be due to reasons such as growth, color variations, asymmetry, signs of discomfort during dermatoscopic examination, or itching, pain, or bleeding.
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| MELTUMP |
HOW IS A MELTUMP TREATED?If the dermatologist finds a mole suspicious, the entire mole is usually removed and sent to a pathologist.
If the pathologist diagnoses MELTUMP, they recommend excising the mole more widely, with a safety margin of at least 5 mm around the scar, and if this is easy (in areas with ample space, not on the face) with a margin of 1 cm (similar to melanoma).WHAT ARE THE OUTLOOK FOR A MELTUMP?Once a MELTUMP has been completely removed, the treatment is complete. Follow-up is not necessary for a MELTUMP. It's sufficient to check the skin yourself and, if new or changed spots appear, consult your doctor or dermatologist.WHAT CAN YOU STILL DO YOURSELF?Prevent sunburn. Check your skin regularly and see your doctor if you see a new or suspicious spot.SAMPUS AND IAMPUSSAMPUSIAMPUS and MELTUMP are essentially the same as MELTUMP, the only difference being that the lesions are not tumors (not raised or deep-growing), but rather superficial . They usually appear as slightly raised spots or completely flat pigmented patches. These, too, are diagnoses that can only be made retrospectively, by a pathologist, after the tissue has been examined.
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| SAMPUS |
SAMPUS |
SAMPUS (dermoscopy) |
SAMPUSmeans superficial atypical melanocytic proliferation of uncertain significance .IAMPUSmeans intraepidermal atypical melanocytic proliferation of uncertain significance .SuperficialThis means that the lesion continues to grow superficially and does not penetrate any deeper. Intraepidermal means that the lesion is even more superficial, only in the top layer of the skin, the epidermis . The layer below that is called the dermis . Between the epidermis and the dermis is a very thin but strong layer called the basement membrane . If tumor cells remain within the epidermis ( intraepidermal ) and do not penetrate that layer, that is good news because there is no risk of deep growth or metastasis.
There is also a form of melanoma that remains within the epidermis (intraepidermal) and does not penetrate the basement membrane. This is called lentigo maligna .
AIMPAIMPstands for atypical intraepidermal melanocytic proliferation . This is a descriptive term used only by pathologists. It indicates an increase in atypical (not entirely normal but abnormal) melanocytes in the epidermis.STUMPSTUMPmeans: Spitz tumor of uncertain malignant potential . To understand what a STUMP is, it must first be explained what a Spitz tumor is. There are 3 different Spitz tumors: a Spitz nevus , an atypical Spitz nevus , and a Spitz melanoma .
Spitz nevus
A Spitz nevus is a mole that is made up of melanocytes that have a special elongated shape . These are also called spindle cell melanocytes. The name comes from the dermatologist Spitz who first described the mole. A Spitz nevus is a benign, rare mole that occurs in children and young adults. A Spitz nevus looks like a pink, red or reddish-brown, symmetrical round bump of about 5 mm. The Spitz nevus is mainly found on the face, neck or on the legs. There is also a rare variant in which several Spitz nevi are grouped in one area. There is also a variant that is very dark brown to black and flat. This is also called a Reed's nevus . A Reed's nevus is usually found on an arm or leg. Its size can vary, up to 1 cm in circumference.
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| Spitz nevus |
Spitz nevus |
Spitz nevus |
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| Spitz nevus |
Spitz nevus |
Reed's nevus |
Atypical Spitz nevus
An atypical Spitz nevus (atypical Spitz nevus, atypical Spitzoid tumor) is a mole made up of the same elongated melanocytes, but the difference is that these cells are atypical , restless . The melanocytes show characteristics that point to malignant behavior, but too few to make the diagnosis of melanoma. The pathologist can also make the distinction between mildly atypical or severely atypical.
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| atypical Spitz nevus |
atypical Spitz nevus |
If a diagnosis of atypical Spitz nevus is made, it is usually advised to remove the nevus in its entirety, if this has not already been done, with a safety margin of a few millimeters to 5 mm.Spitz melanoma / Spitzoïd melanomaA Spitz melanoma is also composed of elongated, spindle-shaped melanocytes, but in this case, malignant cells are clearly present. It is a variant of melanoma and should be treated as such. The lesion should be removed again, leaving a 1 cm safety margin around the scar.
STUMP
A STUMP ( Spitz tumor of uncertain malignant potential ) is a tumor composed of elongated melanocytes, in which, as with MELTUMP, the pathologist cannot easily distinguish between benign and malignant. A STUMP could therefore be a Spitz melanoma, and should therefore be treated just like a melanoma. However, there is a difference: extensive research has shown that with STUMP, it is not necessary to maintain a large safety margin of 1 cm; 5 mm is sufficient.
Furthermore, research is currently underway to determine whether re-excision of melanomas with a safety margin of 1 cm, and sometimes even 2 cm, is really necessary. The guidelines on this point may change.
MELANOCYTOMASIn 2018, the WHO proposed melanocytoma as a new term for skin lesions that fall between benign moles and malignant melanomas. This term is still not universally accepted. The older terms are also still in use. However, it is possible that in the future, the term melanocytoma will be used instead of atypical or dysplastic nevus. The WHO also distinguishes between melanocytomas with few atypical features ( low-grade melanocytoma ) and melanocytomas with many atypical features ( high-grade melanocytoma ). For low-grade melanocytoma, the recommendation is to excise the lesions with a margin of a few millimeters (1-3 mm). For high-grade melanocytoma, the recommendation is to excise the lesions with a margin of at least 5 mm (5-10 mm).
Spitz melanocytoma: The term melanocytoma is also increasingly used
for Spitz tumors . The current term for lesions that fall between a benign Spitz nevus and a malignant Spitz melanoma is atypical Spitz nevus (atypical Spitz nevus) or atypical Spitzoïde tumor . The WHO proposes replacing this term with Spitz melanocytoma , which can also be subdivided into low-grade Spitz melanocytoma and high-grade Spitz melanocytoma .
This new classification also has new consequences. The policy that suspicious pigmented skin lesions are always first removed in their entirety with a narrow margin of 2 mm and sent to the pathology lab has not changed. If the result is Spitz nevus, no further action is necessary, because it is a benign mole. If the result is low-grade Spitz melanocytoma, no further action is necessary, because the 2 mm margin is sufficient. If the result is high-grade Spitz melanocytoma, the advice is to re-excise the area with a margin of at least 5 mm (5-10 mm).Other melanocytomasOther melanocytomas exist, such as pigmented epithelioid melanocytoma , deep penetrating melanocytoma , and BAP1-inactivated melanocytoma , but they are all very rare. |
