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Eruptive seborrheic keratosis: A perilous clue

An abrupt increase in seborrheic keratoses in patients with an underlying malignancy is called the Leser-Trélat sign.


An abrupt increase in seborrheic keratoses in patients with an underlying malignancy is called the Leser-Trélat sign KAUSHIK AND COLLEAGUES
unremarkable epidermis with clusters of pleomorphic tumor cells in the dermis (Figure 3a) arranged in small glands inciting a desmoplastic reaction (Figure 3b). The tumor cells had coarse chromatin and a moderate amount of cytoplasm. Immunostaining results were positive for cytokeratin 7 (Figure 3c). Overall, the features suggested a possible adeno carcinoma.
The patient underwent whole-body 18 Ffl uorodeoxyglucose (FDG) positron emission tomography with contrast-enhanced computed tomography, which revealed a soft-tissue mass lesion with speckled calcifi cation in the right middle lobe of the lung. The lesion was FDG-avid (ie, with high uptake of FDG), heterogeneously enhancing, and lobulated. The lesion reached up to the hilum, abutting the mediastinum and encasing the right middle lobe bronchus.
There were FDG-avid lymph nodes in the right axillary and supraclavicular regions, a single FDG-avid lesion in the left adrenal gland, and multiple subcutaneous and muscular deposits distributed in the chest wall, left thigh, right gluteal region, and upper back.
Based on those results, we made a diagnosis of metastatic non-small-cell lung cancer, adenocarcinoma type, not otherwise specifi ed. Palliative chemotherapy with paclitaxel and carboplatin was started, and the patient received oncology follow-up care. Response to chemotherapy could not be ascertained, as the patient was lost to follow-up owing to COVID-19-related lockdown.

■ ERUPTIVE SEBORRHEIC KERATOSIS
An abrupt increase in the size and number of seborrheic keratoses in patients with an underlying malignancy is called the Leser-Trélat sign. More than 50% of associated malignancies are adenocarcinomas, especially those of the stomach, colon, rectum, and breast, 1 although this sign has also been reported in other malignancies, including lung cancer. 2 The association of the Leser-Trélat sign with malignancy is debatable, with suggestions that the sign may exist independent of an underlying occult malignancy or may be associated with nonmalignant conditions such as benign neoplasms, pregnancy, or human immunodeficiency virus infection. 3,4 The exact pathogenesis of the Leser-Trélat sign is unclear. One hypothesis attributes it to growth factors released by tumor cells, such as growth hormone, epidermal growth factor, and transforming growth factor alpha. Another suggests that extracellular matrix components, such as glycosaminoglycans released from stroma of the tumor, become incorporated in distant normal skin, causing epithelial alteration and eruption of seborrheic keratoses. 5 The Leser-Trélat sign may be the initial presentation, or it can be detected concurrently with or after diagnosing an internal malignancy. Eruptive seborrheic keratoses can occur anywhere, but the most common sites are the back, chest, and extremities. 5

ERUPTIVE SEBORRHEIC KERATOSIS
Evaluation of a patient with the Leser-Trélat sign should begin with a detailed history and clinical examination. Special investigations should be performed to look for the occult primary malignancy.
Our patient was apparently doing well except for the relatively abrupt appearance of multiple eruptive seborrheic keratoses, which prompted us to investigate further for an occult malignancy. The nodule on his chest wall could not be explained by the Leser-Trélat sign and thus was biopsied. The results helped us reach the fi nal diagnosis.
Despite the nonspecifi c nature of the Leser-Trélat sign, our case exemplifi es the importance of performing a thorough evaluation in patients presenting with sudden-onset eruptive seborrheic keratoses. ■ ■ DISCLOSURES