Scalp Metastasis as the First Sign of Small-Cell Lung Cancer: Management and Literature Review

Cutaneous metastasis from primary visceral malignancy is a relatively uncommon clinical entity, with a reported incidence ranging from 0.22% to 10% among various series. However, the presence of cutaneous metastasis as the first sign of a clinically silent visceral cancer is exceedingly rare. We describe here a case of an asymptomatic male patient who presented with a solitary scalp metastasis as the initial manifestation of an underlying small-cell lung cancer. Diagnostic evaluation revealed advanced disease. We conclude that the possibility of metastatic skin disease should always be considered in the differential diagnosis in patients with a history of smoking or lung cancer presenting with cutaneous nodules. Physicians should be aware of this rare clinical entity, and appropriate investigation should be arranged for early diagnosis and initiation of the appropriate treatment. The prognosis for most patients remains poor.Key words: Small cell lung carcinoma, Scalp, MetastasisCutaneous metastasis from a primary visceral malignancy is a relatively uncommon clinical entity, with a reported incidence ranging from 0.22% to 10% among various series.^1–10 In a meta-analysis of 7 studies comprising a total of 20,380 patients, Krathen et al⁵ found that the overall incidence of cutaneous metastasis was 5.3% and that the most common tumor to metastasize to the skin was breast cancer.⁵ Cutaneous involvement may occur due to direct extension of the tumor as a local metastasis or as a distant metastasis,⁹ and it has been associated with advanced disease and poor prognosis.^3,4,11–13 Half of the patients with cutaneous metastases die within the first 6 months after the diagnosis, whereas lung cancer has been associated with the poorest prognosis.¹⁴ Cutaneous metastasis as the first sign of an internal malignancy is an exceedingly rare occurrence. It has been reported to occur in only 0.8% of the cases and has been associated with advanced disease.¹⁵ Skin metastasis from lung cancer is a rare clinical entity that has been reported to occur in 0.22% to 12% of patients with lung cancer.^{1–4,6,10,15–17} In most cases, metastases occur after the initial diagnosis and treatment of the primary lung tumor.¹⁷ Skin metastasis as the initial manifestation of an underlying lung cancer is a very rare occurrence.^4,6,16,17 We describe herein an exceedingly rare case of an asymptomatic male patient who presented with a solitary scalp metastasis as the initial manifestation of an underlying small-cell lung cancer. Diagnostic evaluation and management are discussed along with a review of the literature.

Case Presentation

A 74-year-old man presented with a 2-month history of a slowly growing, painless nodule in his right temporal region. His past medical history was significant for arterial hypertension. He was a heavy smoker but had no history of lung disease. He denied any respiratory symptoms, fever, or weight loss, and his general condition was good.Clinical examination revealed a painless, movable, nonulcerated nodule in the right temporal region measuring approximately 2 cm in diameter. There were no signs of infection and the overlying skin was normal. A chest X-ray showed a large mass occupying the upper lobe of the left lung. Subsequent computed tomography (CT) showed a large mass involving the left upper lobe associated with extensive mediastinal lymphadenopathy. In addition, a head CT revealed 3 metastatic brain lesions.The scalp lesion was easily resected down to the epicranial aponeurosis. Histopathologic examination and detailed immunohistochemical analysis revealed extensive infiltration from small-cell lung carcinoma (Fig. 1). Immunohistochemically, the tumor cells were strongly positive for TTF-1 and cytokeratin 8.18 and focally positive for CD56 and synaptophysin (Fig. 2). A CT-guided biopsy of the lung tumor confirmed the presence of a small-cell lung carcinoma, and the patient was advised to start chemotherapy and radiotherapy. Unfortunately, although he completed the first cycle of chemotherapy, he refused to continue and was subsequently lost to follow-up.Open in a separate windowFig. 1Histopathologic findings. (1A) Typical appearance of small-cell carcinoma. Small hyperchromatic nuclei and squeezing artifact [hematoxylin and eosin (H&E) ×100]. (1B) Whole-mount section showing large metastatic infiltration of dermis leaving surprisingly unaffected the epidermis (H&E ×25). (1C) Note the border between neoplastic cells (left) and the basal layer of epidermis (right; H&E ×200).Open in a separate windowFig. 2Immunohistochemical analysis. (2A) Strong nuclear positivity for TTF-1 (original magnification ×400). (2B) Diffuse cytoplasmic reactivity for cytokeratin 8/18 (original magnification ×400). (2C) Many of the neoplastic cells show membranous-pattern positivity for CD56 (original magnification ×200). (2D) Focal cytoplasmic positivity for synaptophysin (original magnification ×400).