|LETTER TO EDITOR
|Year : 2021 | Volume
| Issue : 2 | Page : 415-416
Skin metastasis of lung cancer: There's more to it than meets the eye
Saurabh Karmakar, Priya Sharma, H Ameet
Department of Pulmonary Medicine, All India Institute of Medical Sciences, Patna, Bihar, India
|Date of Submission||09-May-2021|
|Date of Decision||10-May-2021|
|Date of Acceptance||24-May-2021|
|Date of Web Publication||30-Jun-2021|
Room No. 330, Pulmonary Medicine OPD, 3rd Floor, New OPD Building, All India Institute of Medical Sciences, Phulwari Sharif, Patna - 801 505, Bihar
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Karmakar S, Sharma P, Ameet H. Skin metastasis of lung cancer: There's more to it than meets the eye. Cancer Res Stat Treat 2021;4:415-6
We read the article titled, “Non-small-cell lung cancer metastasis to unusual sites: A retrospective case series” by Ganguly et al. with interest. The authors have performed a retrospective analysis of patients with non-small-cell lung cancer NSCLC with metastases to unusual sites. Niu et al. from mainland China, in their retrospective study on patients with NSCLC, observed that metastases to unusual sites were more likely to be diagnosed later in the disease course and were metachronous in nature. This is in contrast to the observations reported in Ganguly et al.'s study, where all the patients had metastases to unusual sites at the time of diagnosis. The possible reasons for this difference among patients of Asian descent need elucidation.
The skin and soft tissue were the most common unusual sites of metastasis. Most of the data on skin metastases from across the world have been obtained from autopsy or retrospective series, and the study by Ganguly et al. seems no different.
In a retrospective study of patients with skin metastases from solid tumors, the lung was the second most common site of tumor origin; these patients had a median survival of 2.9 months. Analyses by the Eastern Cooperative Oncology Group and the European Lung Cancer Working Party and studies by Hickish et al. and Hoang et al. have shown skin and subcutaneous metastases to be associated with a worse prognosis.
Positron-emission tomography–computed tomography (PET-CT) provides information about the morphology and metabolic activity of skin metastases; it can also unmask subtle recurrences, micrometastases, and indeterminate nodal metastases. 18F-fludeoxyglucose (18F-FDG) PET imaging may detect clinically occult skin metastases. Skin metastases manifest as FDG-avid skin thickening or subcutaneous nodules. PET-CT has higher sensitivity than CT and magnetic resonance imaging (MRI) for the detection of metastases. Skin metastases can mimic other primary skin malignancies or benign entities. As there is a possibility of a false-positive FDG uptake, contrary to Ganguly et al.'s opinion, a biopsy is essential for confirming the presence of metastases. In the case series by Ganguly et al., a tissue biopsy from the unusual site was performed only for 17 (14.6%) patients to confirm whether the lesion had metastasized from the lung primary tumor. Therefore, we request the authors to provide a reason for their low application of biopsy.
Biopsy and immunohistochemistry (IHC) are reliable tools for the diagnosis of skin metastases. IHC using antibodies against p63, B72.3, calretinin, and cytokeratin 5/6 can differentiate skin metastases from primary skin adnexal tumors.
Ganguly et al. reported the occurrence of brain metastases in 14 (11.5%) patients. In this study, the brain was considered an uncommon site of metastasis. However, population-based cancer registries have reported the brain to be the most common site of metastasis in patients with lung cancer, with about 10% of the patients presenting with brain metastases at diagnosis. Asymptomatic brain metastases are present in 1% of the patients with Stage IA NSCLC and 21% of those with Stage IIIA NSCLC. Although in Ganguly et al.'s study, a brain MRI was performed for all patients with localized disease, the reason for the low prevalence of brain metastases in their study has not been elucidated. In addition, a mention of the extent of the use of imaging modalities such as CT, MRI, and PET/CT for the detection of metastases to unusual sites could have provided valuable information about the optimum modality to be used for a particular site.
Thus, metastases discovered incidentally or by imaging need further characterization and histological confirmation to establish the site of the primary tumor and extent of the metastatic lesions and to devise appropriate treatment programs.
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Conflicts of interest
There are no conflicts of interest.
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Non-small-cell lung cancer metastasis to unusual sites: A retrospective case series. Cancer Res Stat Treat 2021;4:50-4. [Full text]
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