Deep Benign Fibrous Histiocytoma of the Anterior Mediastinum Mimicking Malignancy

Abstract

The following report describes the case of a 43-year-old male smoker that was referred to the rapid access lung clinic with haemoptysis, chest pain, and axillary lymphadenopathy-a clinical picture that raised concern for a possible underlying malignancy. Preliminary investigations revealed elevated D-dimers, low-volume haemoptysis, and a normal chest X-ray, which lowered the index of suspicion. However, computed tomography (CT) pulmonary angiogram identified a right hilar mass, several parenchymal cysts, and a large mediastinal mass. In addition, a left-sided adrenal lesion was also discovered following CT abdomen pelvis, potentially indicating metastatic disease. Fortunately, a positron emission tomography scan failed to detect any metabolic activity in either the right hilar mass, left adrenal lesion or the anterior mediastinal mass. CT-guided biopsy identified the mediastinal mass as a low-grade spindle cell tumour. Due to its large size, the mass was surgically resected and confirmed to be a deep benign fibrous histiocytoma. The significance of this report is to highlight a clinical presentation suggestive of malignancy but actually resulting from a rare variant of a benign tumour. The constellation of regional lymphadenopathy, respiratory and gastrointestinal symptoms, lung cysts, an adrenal tumour, and a mediastinal mass appeared to suggest a progressive disease pattern more commonly associated with malignancy.

Mesenchymal Tumors of the Mediastinum: An Update on Diagnostic Approach

“…Approximately 10% of cases arise in visceral soft tissue. Mediastinal DFHs have also been reported 112–114. Rearrangements involving either PRKCB or PRKCD (members of the gene family encoding PKC) have been identified in several morphologic subtypes of benign FH, including DFH 115,116…”

“…Mediastinal DFHs have also been reported. [112][113][114] Rearrangements involving either PRKCB or PRKCD (members of the gene family encoding PKC) have been identified in several morphologic subtypes of benign FH, including DFH. 115,116 Histologically, DFH is more cellular than typical cutaneous FH.…”