Subungual Tumors

 

Purpose or Learning Objective: To review clinical and radiologic characteristics of subungual tumors.

Methods or Background: Subungual tumors may present specific imaging findings.

Results or Findings:

Subungual glomus tumors develop from the neuromyoarterial glomus body, occurring three times more often in females than in males and typically in the fourth to fifth decade. Patients frequently present with subungual pain and temperature sensitivity. Glomus tumors on radiographs may present as a focal bone erosion. They are delineated on ultrasonography (US) and magnetic resonance imaging (MRI) with a high diagnostic sensitivity. Imaging features on US are sharp demarcation, hypoechogenicity, and hypervascularity on Doppler. The corresponding characteristics on MRI are very high signal on T2-weighted sequences and early contrast enhancement.

Hemangioma is a tumor of vascular origin in younger and middle-aged patients. Phleboliths and bone erosion are infrequently visualized on radiographs. On US, hemangiomas present as a heterogeneous hypoechogenic mass due to fatty content and/or phleboliths, as well as hypervascularity on Doppler. MRI shows an intermediate signal on T1-weighted and striking hyperintensity on T2-weighted images. There may be some heterogeneous signal due to fatty components, as well as flow voids and serpentine patterns caused by vessels. Importantly, delineation of macroscopic fat on MRI is very unlikely, probably due to the small size of subungual hemangiomas.

Chondromas most commonly occur in the third to sixth decade. Radiographically, the lesion often presents with calcifications. On US, chondromas are sharply demarcated with a heterogeneous hypoechogenicity and hypervascularity on Doppler. On MRI, the lobulated tumor exhibits intermediate signal on T1-weighted and hyperintensity on T2-weighted images, as well as vivid contrast enhancement. There may be some foci with low signal intensity on all MRI sequences due to calcifications.

Further rare benign subungual tumors to consider are the superficial acral fibromyxoma and keratoacanthoma.

Subungual malignancies include a malignant melanoma. If it presents with subungual pigmentation, it may already be suspected clinically. On MRI, melanin content typically demonstrates high signal on T1-weighted images. However, in the subungual space, melanomas are frequently amelanotic and/or exhibit intratumoral hemorrhage, complicating assessment clinically and on imaging. Squamous cell carcinoma is another relatively common primary malignant subungual tumor. Rarely, bone metastases or sarcomas may present in this space.

Non-neoplastic tumors include epidermal and mucoid cysts. Infection, particularly an abscess, should be considered as a differential diagnosis in subungual lesions if there are corresponding clinical symptoms.

Conclusion: Radiographs, US, and MRI are the modalities of choice for the diagnostic work-up of subungual tumors.

Publication History

Article published online:
26 May 2023

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