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Updated: Aug 7, 2025
A Robust Discovery Platform for the Identification of Novel Mediators of Melanoma Metastasis
Published on: March 8, 2022
Analysis of PRAME immunocytochemistry in 109 acral malignant melanoma in situ
Qiu-Ju Miao1, Jie Zang1, Xue-Bao Shao1
1Department of Pathology, Chinese Academy of Medical Sciences and Peking Union Medical College Institute of Dermatology, Nanjing, Jiangsu, China.
Aims:
Preferentially expressed antigen in melanoma (PRAME) recently is a reliable immunohistochemistry (IHC) marker for distinguishing melanoma from other lesions. However, there are few articles focused on PRAME use in acral malignant melanoma, the most common type in Asians. This study investigated PRAME IHC expression in a large series of acral malignant melanoma in situ to add to the body of clinical knowledge.
Methods:
PRAME IHC was performed in unequivocal cases of primary acral lentiginous melanoma in situ (ALMIS), subungual melanoma in situ (SMIS) and acral recurrent nevi as the control. PRAME tumour cell percentage positivity and intensity were expressed as categorised in a cumulative score by adding the quartile of positive tumour cells to intensity labelling. The final IHC expression was interpreted as negative (0-1), weak (2-3), moderate (4-5) or strong (6-7).
Results:
In 91 ALMIS patients, 32 cases (35.16%) were strong, 37 (40.66%) were moderate and 22 (24.18%) were weak. In 18 SMIS patients, strong positivity of PRAME was observed in 4 (22.22%) cases, moderate in 10 (55.56%) and weak in the remaining 4 (22.22%). No melanoma sample was negative for PRAME. By comparison, only 2 of the 40 acral recurrent nevi cases were positive.
Conclusions:
Our study supports the ancillary value of PRAME for diagnosing ALMIS and SMIS with high sensitivity and specificity.
Insights
Preferentially expressed antigen in melanoma (PRAME) is a sensitive and specific immunohistochemistry marker for diagnosing acral lentiginous melanoma in situ (ALMIS) and subungual melanoma in situ (SMIS). PRAME expression was consistently observed in melanoma cases, unlike in benign nevi.
Area of Science:
- Dermatopathology
- Oncology
- Immunohistochemistry
Background:
- Preferentially expressed antigen in melanoma (PRAME) is an emerging immunohistochemistry (IHC) marker for melanoma diagnosis.
- Acral malignant melanoma, particularly acral lentiginous melanoma in situ (ALMIS) and subungual melanoma in situ (SMIS), is prevalent in Asian populations.
- Limited studies have focused on PRAME's utility in acral melanoma subtypes.
Purpose of the Study:
- To evaluate the diagnostic utility of PRAME immunohistochemistry (IHC) in acral lentiginous melanoma in situ (ALMIS) and subungual melanoma in situ (SMIS).
- To assess the sensitivity and specificity of PRAME as a marker for distinguishing acral melanomas from benign acral nevi.
- To contribute clinical knowledge regarding PRAME expression in a large cohort of acral melanoma cases.
Main Methods:
- PRAME IHC was performed on unequivocal cases of primary ALMIS, SMIS, and acral recurrent nevi (control).
- Tumor cell percentage positivity and intensity were scored cumulatively.
- IHC expression was categorized as negative (0-1), weak (2-3), moderate (4-5), or strong (6-7).
Main Results:
- All 91 ALMIS cases and 18 SMIS cases showed PRAME positivity (weak, moderate, or strong).
- In contrast, only 2 out of 40 acral recurrent nevi cases exhibited PRAME positivity.
- PRAME expression was consistently detected across all melanoma samples, with varying degrees of intensity.
Conclusions:
- PRAME immunohistochemistry demonstrates high sensitivity and specificity for diagnosing ALMIS and SMIS.
- PRAME serves as a valuable ancillary marker in the histopathological diagnosis of acral melanomas.
- The findings support the routine use of PRAME IHC in evaluating challenging acral skin lesions.
