Spindle cell subtype of pulmonary clear cell tumor with prominent calcification and malignant potential

Malignant lung PEComa (clear cell tumor): rare case report and literature review

Clear cell tumors of the lung (CCTL), or "sugar tumors" of lung, are very uncommon lesions and are mostly benign perivascular epithelioid cell (PEC) tumors with no specific morphologic features. Fewer than 100 cases have been reported; the aggressive nature demonstrated in sporadic reports has rarely been described in the literature. Although the course is generally described as benign, eight reported cases showed malignant behavior. We report a case of a PEC with a malignant presentation in a young man, correlating the main characteristics of the tumor with other cases reported in the literature to better elucidate this rare presentation. We also performed a literature review of reports on benign and malignant CCTL cases, with a focus on clinical, imaging, and immunohistochemical differentiation. CCTLs are rare tumors that require histopathological and immunohistochemical confirmation; to date, criteria that can predict malignant evolution are lacking.

Primary Perivascular Epithelioid Cell Tumor of the Lung: A Case Report

Perivascular epithelioid cell tumors (PEComas) are very rare mesenchymal neoplasms, composed of histologically and immunohistochemically distinctive cells that form a sheet-like appearance around vessel lumens. Although most are benign, a malignant subset does exist, complicating clinical diagnostic efforts. Proper evaluation and management are thus essential for long-term patient survival. Herein, we present a rare case of a benign pulmonary PEComa that was diagnosed postoperatively in a 45-year-old woman.

Clear cell "sugar" tumor of the lung: Diagnostic characteristics of a rare pulmonary tumor: A case report and review of literature

INTRODUCTION

Clear cell tumors of the lung (CCTLs), also known as "sugar tumors" for an abundant cellular glycogen concentration, are an extremely rare type pulmonary neoplasm. Often, they are incidentally found on chest roentgenogram or computed tomography scan during routine examination. CCTLs usually present with nonspecific symptoms that pose a diagnostic challenge to clinicians. Accordingly, histopathology remains the gold standard for diagnosing. Moreover, some of them can present with either appearances or histopathological features similar to other pulmonary neoplasms under the light microscope, including pulmonary malignancy, thereby causing misdiagnosis prior to or after surgery. Accordingly, herein, we describe a rare case of CCTL, review the literature has been published, and then discuss the benign versus malignant nature of this rare tumor.

PATIENT CONCERNS

A 59-year-old man presented due to a high-density chest nodule in the left diaphragm. The patient's medical history was unremarkable and he also denied smoking in the past.

DIAGNOSIS

Physical examination, there were no noted signs. A new chest contrast-enhanced computed tomography revealed a 3.2 × 2.5 cm, solitary, circular nodule with a smooth edge located in the beside of the left thoracic aorta. Postoperative pathological and immunohistochemical examinations of the surgical specimens revealed a final diagnosis of CCTLs.

INTERVENTIONS

The patient underwent video-assisted thoracoscopic surgery. A wedge resection of left lower lung lobe was carried out and the tumor node was successfully removed alongside normal surrounding parenchyma.

OUTCOMES

The operation was successful. Then the patient recovered completely and continued to do well on postsurgical thoracic surgical clinic visits. The tumor was a benign tumor, and the patient did not require any additional treatment. The patient had been followed-up regularly for 4 years after surgery; she did not experience any complications and remained disease-free.

CONCLUSION

CCTLs should be considered in the differential diagnosis if a patient shows a solitary, circular chest nodule with a smooth edge. They are extremely rare lung tumors that must be differentiated from other lung tumors, especially the malignant tumors. Although pathological and immunohistochemical findings are important for making the diagnosis, the varying histopathological features on microscope make diagnosis difficult. The current case highlights the importance of physicians being aware of and suspecting CCTLs in similar cases, along with knowing the characteristics of CCTLs for the diagnosis and differential diagnosis.

Perivascular epithelioid cell tumor of the lung: A case report and literature review

The perivascular epithelioid cell tumor (PEComa) is a rare tumor of interstitial origin characterized by several immunological and muscle cell markers. The clear cell sugar tumor (CCST) of the lung is a type of PEComa defined by thin cell walls and high levels of glycogen in the cytoplasm. We herein reported the case of a 48‐year‐old male with a recurrence of lung CCST. The preoperative diagnosis of the lung mass was performed by percutaneous needle biopsy. During the thoracoscopic resection, multiple adhesions in the thoracic cavity were described. The tumor invaded the chest wall, and the boundaries between the tumor and surrounding normal tissues were unclear. The mediastinal lymph nodes were significantly enlarged. No relevant gene mutations were detected. After concomitant chemoradiotherapy, the patient's condition was stable. We also conducted a literature review and discussed the overall findings.

Extensive calcification in adenocarcinoma of the lung: A case report

Calcification in lung nodules usually indicates a benign lesion. Here, we report the case of a 59‐year‐old male patient with a well defined 30 mm calcified nodule in his right upper lung lobe and calcified mediastinal lymph nodes. The mass was diagnosed as adenocarcinoma by transbronchial biopsy. He received systemic chemotherapy, followed by lobectomy and mediastinal lymph node dissection. During surgery, the lymph nodes were tightly adherent to the superior vena cava with invasion of the vascular wall. Pathological diagnosis confirmed acinar adenocarcinoma and psammoma bodies (PBs). Immunohistochemical analysis revealed tumor cells positive for parathyroid hormone‐related proteins 1 and 2. Calcification of primary lung adenocarcinoma is rare. We report a calcified lesion where the secretion of parathyroid hormone by the tumor may have caused the accumulation of PBs. Calcification of metastatic lymph nodes may increase the risk of adhesion, requiring care during surgery.

Key points

Significant findings of the study

Lung adenocarcinoma with extensive calcification in primary and metastatic lymph node lesions is rare and the mechanism involved is poorly understood. Of significance, calcification in our case was related to parathyroid hormone‐related proteins 1 and 2 secreted by the tumor.

What this study adds

This study suggests the potential role of parathyroid hormone‐related proteins in lung tumor calcification. The implications for clinicians are that calcified metastatic lymph nodes and tumors might be tightly fused to tissues. Therefore, surgery should be conducted with care.

Malignant perivascular epithelioid cell tumor of the lung synchronous with a primary adenocarcinoma: one case report and review of the literature

BACKGROUND

Perivascular Epithelioid Cell Tumors (PEComa) is an extraordinarily rare mesenchymal neoplasm especially the malignant type originating from the lung. To date, only 8 cases of malignant or malignant potential pulmonary PEComa had been documented. Firm diagnostic criteria for malignant pulmonary PEComa need urgently to be established.

CASE PRESENTATION

We report a challenging case of malignant pulmonary PEComa combined with a primary adenocarcinoma in a 54-year-old man. The PEComa-like tumor showed strong Melan-A and weak transcription factor E3 (TFE3) protein expression but no TFE3 gene rearrangement. The carcinoma-like nodule was recognized as a poorly differentiated primary lung adenocarcinoma.

DISCUSSION AND CONCLUSIONS

Our case report was the first case of malignant pulmonary PEComa synchronous with a primary adenocarcinoma and studied the dilemma of diagnosing benign versus malignant criteria for this uncommon tumor.