Not Just Skin Deep: Small Cell Carcinoma Presenting as Skin Metastases

Authors:
Beverly Patuwo Lee, MD, MPH; Jonathan Huang, MD; and Lee B. Lu, MD

Citation:
Lee BP, Huang J, Lu LB. Not just skin deep: small cell carcinoma presenting as skin metastases. Consultant. 2017;57(6):348-350.

Skin metastases rarely present as the initial clinical manifestation of an underlying small cell carcinoma of the lung. The presence of such dermatologic findings signifies an advanced stage of disease progression and carries a poor prognosis. Therefore, it is crucial for clinicians to understand its significance and to perform early biopsies of any suspicious skin lesions. This late stage of progression is typically deemed incurable, and treatment with chemotherapy is the only option known to slow the progression of disease. We report a case of multiple cutaneous metastases in a previously healthy woman who was later found to have small cell carcinoma, likely originating in the lungs, along with additional organ involvement.

Case Report

A 28-year-old woman presented for evaluation of worsening left lower extremity swelling, pain, and the appearance of multiple nodules and masses on her body over the past 6 months. One month prior to presentation, she reported having received a diagnosis of neurofibromatosis from an outside physician. She denied any known family history of malignancies or dermatologic conditions. She denied any history of smoking.

Figure 1. Diffuse goiter secondary to metastatic small cell carcinoma.

Physical examination revealed a diffuse goiter (Figure 1) and 2 nontender, 4 × 4-cm, smooth masses located anterior to the right tragus and on the right anterior shoulder (Figures 2 and 3). On her scalp and below both breasts were multiple 3 × 3-cm, erythematous, irregular masses (Figures 4 and 5). Her left lower leg was enlarged to 25 cm in diameter at the thigh, with multiple, superficial 2 × 2-cm nodules located on the anterior thigh (Figure 6). Biopsy results of the shoulder mass and the goiter revealed small cell carcinoma.

Figure 2. Smooth, nontender masses on the right anterior shoulder.

Figure 3. Smooth, nontender masses located anterior to the right tragus.

Figure 4. Irregular erythematous masses on the scalp.

Figure 5. Irregular erythematous masses below both breasts.

Figure 6. Enlarged left lower extremity secondary to lymphatic involvement of metastases, with multiple superficial nodules located on the anterior aspect of the left thigh.

Computed tomography scanning revealed the presence of extensive adenopathy, a 2 × 3-cm left upper lobe lung mass that was peripherally located, and metastatic lesions in the brain, liver, adrenal glands, kidneys, and left lower extremity. Echocardiography revealed an additional 3 × 4-cm tumor occupying nearly the entire left atrium. The patient declined further workup and palliative chemotherapy, and she was discharged for home hospice care.

Discussion

Internal malignancies leading to skin metastases are rare, with a reported incidence of 2% in 5 large autopsy studies.¹ Of all visceral neoplasms, lung cancer is responsible for the majority of skin metastases in men and is the second leading cause of skin metastases in women, after breast cancer. Every histologic type of lung cancer has been associated with the development of skin metastases, although it is debatable whether adenocarcinoma or large cell carcinoma has a greater tendency to metastasize to remote cutaneous sites.^2-4 However, small cell carcinoma of the lung rarely extends to the skin.⁵

The malignant cells of small cell carcinoma often affect regional areas via lymphatic channels but can also disseminate widely throughout the entire body via hematogenous spread.² Metastatic lesions are often found on the anterior chest, head/scalp, back, and abdomen. Less common sites of metastasis are the shoulders, flank, and upper and lower extremities.^6,7 

Cutaneous manifestations of small cell carcinoma do not have classic pathognomonic features; however, they share several general characteristics and are commonly described to be nodular, mobile, fast growing, and painless. They may also present as solitary or multiple lesions with ulcerative or exudative features. Upon biopsy, some metastatic lesions appear to remain superficial, while others invade both the dermis and subcutaneous tissue.⁴ Therefore, it is important to note that the presentations of skin metastases are variable.

Skin findings may be the initial sign of an occult visceral malignancy. From 20% to 60% of skin lesions present before or coincidentally with the detection of a visceral neoplasm.⁷ More specifically, lung carcinoma has been shown to be the fastest visceral malignancy to metastasize to the skin after the initial diagnosis, with a mean time of 5.75 months.⁷ Lung cancer spreads quickly to multiple organs, and it is rare for lung cancer to spread only to the skin. In fact, Triller Vadnal and colleagues² found that only 2 of the 14 patients in their case series had isolated skin metastases. Thus, skin metastases from internal malignancies represent an advanced grade of disease and are associated with a worse prognosis—mean survival time among Triller Vadnal and colleagues’ patients was 4 to 6 months, with a median survival of 85 days from initial detection of the abnormal skin findings.²

Chemotherapy is regarded as the only option to slow the progression of small cell carcinoma. However, studies have shown that chemotherapy only prolongs survival for an additional 2 to 3 months.

Primary care providers are often the first to screen skin lesions in difficult clinical scenarios. Skin changes in patients with a history of lung cancer or with a history of chronic smoking must warrant a high level of clinical suspicion, because early lung cancer may be deceivingly quiescent. Early detection is necessary to differentiate benign soft-tissue neoplasms and malignant metastases and should be pursued when a clinical diagnosis is uncertain.

The diagnostic gold standard is fine-needle aspiration biopsy with histologic examination. Once a patient receives a diagnosis of primary lung cancer with skin metastases, the disease is often deemed unresectable and thus considered incurable.⁵ Factors that denote a poor prognosis include an unresectable primary tumor, small cell primary tumor, multiple cutaneous metastases, and other distant metastases.⁷ Unfortunately, our patient had all 4 of these factors at initial presentation.

Early findings of skin changes may signify a potentially fatal underlying pathology and require rapid diagnostic workup to determine the extent of disease progression.

Beverly Patuwo Lee, MD, MPH, is a pediatric resident physician at Texas Children’s Hospital at Baylor College of Medicine in Houston, Texas.

Jonathan Huang, MD, is an internal medicine physician in Houston, Texas.

Lee B. Lu, MD, is an associate professor of medicine at Baylor College of Medicine in Houston, Texas.

REFERENCES:

1. Coslett LM, Katlic MR. Lung cancer with skin metastasis. Chest. 1990;97(3):​757-759.
2. Triller Vadnal K, Triller N, Požek I, Kecelj P, Košnik M. Skin metastases of lung cancer. Acta Dermatovenerol Alp Pannonica Adriat. 2008;17(3):125-128.
3. Altintoprak F, Baytekin HF, Tasdemir C. Primary small cell carcinoma of the lung presenting with breast and skin metastases. Korean J Intern Med. 2011;26(2):207-209.
4. Kamble R, Kumar L, Kochupillai V, Sharma A, Sandhoo MS, Mohanti BK. Cutaneous metastases of lung cancer. Postgrad Med J. 1995;71(842):741-743.
5. Terashima T, Kanazawa M. Lung cancer with skin metastasis. Chest. 1994;​106(5):1448-1450.
6. Brownstein MH, Helwig EB. Pattern of cutaneous metastases. Arch Dermatol. 1972;105(6):862-868.
7. Mollet TW, Garcia CA, Koester G. Skin metastases from lung cancer. Dermatol Online J. 2009;15(5):1.