Relevance of an incidental chest finding

Abstract

Solitary pulmonary nodule represents 0.2% of incidental findings in routine chest X-ray images. One of the main diagnoses includes lung cancer in which small-cell subtype has a poor survival rate. Recently, a new classification has been proposed including the very limited disease stage (VLD stage) or T1-T2N0M0 with better survival rate, specifically in those patients who are treated with surgery. However, current recommendations postulate that surgery remains controversial as a first-line treatment in this stage. We present the case of a 46-year-old female referred to our hospital with a preoperative diagnosis of a solitary pulmonary nodule. On initial approach, a biopsy revealed a small cell lung cancer. She received multimodal therapy with surgery, chemotherapy, and prophylactic cranial irradiation and is currently alive without recurrence on a 2-year follow-up.

INTRODUCTION

A solitary pulmonary nodule (SPN) is defined as a well-circumscribed round or oval lung opacity of less than 3 cm in diameter, which is completely surrounded by parenchyma and unassociated with atelectasis, lymph node enlargement, pneumonia, or pleural effusion.[1] Differential diagnoses include lung cancer among others.[2] Most of SPNs are incidentally detected (0.2% of chest X-ray). When the diameter is greater than 20 mm, the risk of malignancy can be as high as 82% (Odds Ratio 3.67).[3] Worldwide lung cancer is the first cause of cancer-related mortality. Besides small cell lung cancer (SCLC) represents 13–25% of deaths by lung cancer, is highly sensitive to chemotherapy (CHT) and radiotherapy (RT).[4] On the other hand, surgery as a therapeutic strategy in SCLC is still matter of controversy.[5]

We report the case of a woman in her fifth decade of life referred to our hospital with an incidental SPN finding. A biopsy revealed the presence of SCLC and received a multimodal therapeutic strategy including surgery, adjuvant CHT, and prophylactic cranial irradiation (PCI) with no recurrence over a period of two years of follow-up.

CASE REPORT

A 46-year-old female, referred to our hospital with a SPN in the right upper lobe (RUL) lung, which was incidentally identified during a preoperatory evaluation (umbilical hernia repair). She is a current smoker (4 pack-years) and has a clinical history of hypertension under treatment.

On initial examination her vital signs were normal. An abdominal exam revealed a 2 cm umbilical hernia. A positron emission tomography (PET) of the chest confirmed a hypodense zone in the posterior segment of the RUL positive to [¹⁸F] fluoro-2-deoxy-D-glucose (FDG) with 2.5 standard uptake value (SUV) [Figure 1a].

Figure 1.

(a) PET/CT scan shows a SPN with intense enhancement to FDG in the posterior segment of the right upper lobe; (b) Intrabronchial neoplastic cells disposed as nests-like distribution. Hematoxylin and eosin stain (H and E, 10×)

A nonanatomical resection of the nodule was performed. The pathological diagnosis was SCLC [Figure 1b and 2a]. Staging work-up included a magnetic resonance imaging (MRI) of the brain, abdominal computed tomography (CT), and a radionuclide bone scan (RBS) with no evidence of metastases. Thereafter, the staging was classified as a VLD stage SCLC or T1N0M0. The local surgical consensus decided to make a right-upper lobectomy with lymph-nodes dissection.

Figure 2.

(a) Neoplastic cells with scant cytoplasm, fine chromatin, and round nucleus (H and E, 40×); (b) PET/CT chest scan during follow-up without evidence of recurrence.

Both RUL and lymph nodes showed no residual neoplastic activity. The initial performance status was Karnofsky 70% and ECOG – 1. Adjuvant CHT began with cisplatin/etoposide and after six cycles the performance status improved (Karnofsky 100% and ECOG – 0). Thereafter, was submitted to PCI with a conventional fractionated dose of 20 Gy. A subsequent evaluation with brain MRI showed no evidence of metastases.

During a follow-up period of two years, two PET/CT scans were performed without recurrence [Figure 2b]. Currently, the patient had a complete response (CR) to treatment.

DISCUSSION

Most of the SPN are incidentally detected (0.2% of chest X-rays images). Approximately, 70% of lung cancer manifesting as SPN is located in the lung's RUL.[2] Several morphologic features on CT scans are useful in assessing a nodule's malignant potential including spiculated margins, lobular or irregular contour, heterogeneous attenuation (after contrast injection enhance more than 20 Hounsfield units), the halo sign, and the growth rate among others. According to the American Cancer Society, overall lifetime odds to develop lung cancer are almost 1 in 13 and 1 in 16 for men and woman, respectively, of these between 20% and 30% will present as an SPN.[6]

Recently, it has been suggested to include the VLD stage in the classification of SCLC, which is defined as no preoperative evidence of regional lymph nodes involved.[4,5,7] This reassignment has wide implications on therapeutic strategies because initial randomized data are in favor of using RT over surgery combined with CHT as first-line treatment. However, recent studies have shown a reasonable survival rate in patients who underwent surgery plus CHT as curative-intent therapy for VLD-stage SCLC.[8,9] Most recently, Yu et al. analyzed 247 patients who underwent surgical lobectomy with or without thoracic RT (TRT) for stage I SCLC. Surgery per se offers a 3- and 5-year survival rate of 58% and 50%, respectively, without TRT.[10] Notwithstanding, current evidence-based clinical guidelines have no conclusion on surgery as first-line treatment in cases of VLD-stage SCLC.[5] However, surgeons will undoubtedly continue to offer surgery to T1-T2N0 patients although remains controversial.[11]

Brain metastases (BM) will emerge over the next 2 years in approximately 50%–60% of patients who achieved a CR. A meta-analysis found that the PCI increased 5.4% survival rate at 3 years and reduced the incidence of BM from 59% to 33%. Also a positive effect was found with highest radiation doses (30–36 Gy) applied during 6 weeks after last CHT.[12,13]

During the follow-up, it is recommended to investigate recurrence and metastasis. A useful test is PET/CT which can be used to evaluate recurrence and residual disease during the initial and follow-up investigations. Identification of residual disease that can only be detected by functional imaging could be important in lending salvage therapy opportunity to a specific subset of patients.[14] Any change in the FDG capitation provides information on the evolution of the disease as well as failure or success in treatment.[12,14]

Since the clinical stage of SCLC has a remarkable relevance regarding prognosis and therapeutics implications, an opportune diagnosis is associated with a better survival. Multimodal treatment including surgical management and CHT showed a survival rate in VLD-stage SCLC as high as 50%.[15]

In spite of the controversy related to surgery as initial therapeutic strategy in VLD stage of SCLC, our case represents a successful example of an opportune surgical procedure which has had repercussions in the survival rate of the patient. In a multimodal therapy PCI seem to have an adjuvant role. Functional imaging such as PET may be helpful is this clinical situation, but the scientific validity needs to be prospectively evaluated.