Dots, Circles, and Deception: Radiological Diagnosis of an Unusual Mycetoma

TL;DR

A rare case of mycetoma was diagnosed using imaging features when typical symptoms were absent.

Contribution

Highlights the use of 'dot-in-circle' imaging patterns for diagnosing atypical mycetoma cases.

Findings

Imaging showed 'dot-in-circle' features supporting mycetoma diagnosis in a clinically ambiguous case.

Surgical excision and histopathology confirmed eumycotic mycetoma in the patient.

Early imaging can improve diagnosis when classical symptoms are absent.

Abstract

Mycetoma is a chronic granulomatous fungal or bacterial infection of the subcutaneous tissues, often with a characteristic clinical pattern, but in some patients, the presentation may be subtle or atypical, which can complicate diagnosis. Here, we report an unusual and rare presentation of mycetoma in a 26-year-old male who developed a chronic, progressively enlarging swelling over the leg. The lesion clinically resembled a soft tissue tumor, with no discharging sinuses present throughout the course of evaluation. Initial clinical impression favored a neoplastic or inflammatory etiology rather than an infective process. Ultrasonography and MRI demonstrated focal “dot-in-circle” appearances within the lesion, which supported the diagnosis of mycetoma in this case. The patient subsequently underwent surgical excision of the lesion, and postoperative histopathological examination confirmed the diagnosis of eumycotic mycetoma. This case underscores the importance of recognizing typical imaging features of mycetoma, particularly in the absence of classical clinical findings, to avoid diagnostic delay. Cross-sectional imaging plays a key role in improving diagnostic confidence in early or clinically ambiguous presentations.

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