Cancer Research, Statistics, and Treatment

: 2021  |  Volume : 4  |  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

Correspondence Address:
Saurabh Karmakar
Room No. 330, Pulmonary Medicine OPD, 3rd Floor, New OPD Building, All India Institute of Medical Sciences, Phulwari Sharif, Patna - 801 505, Bihar

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;4:415-416

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Karmakar S, Sharma P, Ameet H. Skin metastasis of lung cancer: There's more to it than meets the eye. Cancer Res Stat Treat [serial online] 2021 [cited 2021 Dec 4 ];4:415-416
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We read the article titled, “Non-small-cell lung cancer metastasis to unusual sites: A retrospective case series” by Ganguly et al. with interest.[1] 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.[2] 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.[3] 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.[3] 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.[4]

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.[5] 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.


1Ganguly S, Ghosh J, Gehani A, Basu A, Chatterjee M, Dabkara D, et al. Non-small-cell lung cancer metastasis to unusual sites: A retrospective case series. Cancer Res Stat Treat 2021;4:50-4.
2Niu FY, Zhou Q, Yang JJ, Zhong WZ, Chen ZH, Deng W, et al. Distribution and prognosis of uncommon metastases from non-small cell lung cancer. BMC Cancer 2016;16:149.
3Juan YH, Saboo SS, Tirumani SH, Khandelwal A, Shinagare AB, Ramaiya N, et al. Malignant skin and subcutaneous neoplasms in adults: Multimodality imaging with CT, MRI, and 18F-FDG PET/CT. AJR Am J Roentgenol 2014;202:W422-38.
4Sariya D, Ruth K, Adams-McDonnell R, Cusack C, Xu X, Elenitsas R, et al. Clinicopathologic correlation of cutaneous metastases: Experience from a cancer center. Arch Dermatol 2007;143:613-20.
5Schoenmaekers JJ, Dingemans AC, Hendriks LE. Brain imaging in early stage non-small cell lung cancer: Still a controversial topic? J Thorac Dis 2018;10:S2168-71.