Tumours of the perionychium

In the authors' institution the main indications for MRI are vascular tumours and mucoid cysts. Numerous other lesions are explored, such as epithelial tumours (warts, epidermoid cysts, onychomatricomas, keratoacanthomas), soft-tissue tumours (fibrokeratomas, fibromas, tenosynovial giant cell tumours), and osteochondral lesions (exostoses, chondromas, osteoid osteomas, chondrosarcomas). The accurate location of the tumour with MRI associated with its signal patterns is important for diagnosis.

Glomus tumours

Glomus tumours develop from the glomus bodies, which are particularly numerous in the dermis of the nail bed. High-resolution MRI is able to depict normal glomus bodies with ^-weighted images and following injection of gadolinium. The classic triad associating pain, tenderness to pressure and cold sensitivity is evocative but infrequent. Imaging appears helpful to the diagnosis in 68% of cases. The mean diagnostic delay, varying from 4 to 7 years in published cases, should be shortened.

The signal behaviour of the glomus tumour depends on its histological composition. These tumours are the result of hyperplasia of one or several elements of the glomus bodies, and they may be considered to be hamartomas. In 1924, Masson described a number of histological variants. These are not routinely mentioned in pathology reports, as they have no prognostic significance; however, knowledge of them is important in evaluating the tumour signal:

1 Vascular tumours are composed of numerous vascular lumens. Enhancement is high after injection of gadolinium, and the signal is high on ^-weighted images. Angiographic MRI shows an early enhancement at the arterial phase, increasing at the delayed venous acquisition (Figure 11.7).

2 Cellular or solid tumours mainly present a proliferation of epithelioid cells (glomus cells) and a relative paucity of vascular lumens. This type of tumour is difficult to detect with MRI. Its signal is close to that of the normal dermis of the nail bed on all sequences. Injection of gadolinium, even with MR angiography, is of little use. Thin, three-dimensional contiguous gradient echo slices are the most helpful by depicting a peripheral capsule or a slight bone erosion on the dorsal aspect of the phalanx (Figure 11.8).

3 Mucoid tumours, with mucoid degeneration of the stroma, present a faint enhancement but have a very high signal on T2-weighted images due to the large amount of water in the stroma (Figure 11.9).

Numerous tumours are a combination of these three elementary types (Figure 11.10). Most often the tumour limits are well defined

Glomus Tumor Finger

Figure 11.7

Highly vascularized subungal glomus tumour. (a) Axial STIR image shows a strongly intense tumour on the midline (arrow) lifting up the nail plate. (b) Axial 7^-weighted slice spontaneously shows a slight increase of signal of the tumor. Note the displaced ventral matrix (arrowhead), the dorsal matrix (small arrows) and the bone erosion of the dorsal cortex (large arrow). (c) Axial postgadolinium 7^-weighted image shows a strong and homogeneous enhancement of the glomus tumor. (d) Magnetic resonance angiography confirms the high degree of vascularization of the tumour on the delayed sequence.

Figure 11.7

Highly vascularized subungal glomus tumour. (a) Axial STIR image shows a strongly intense tumour on the midline (arrow) lifting up the nail plate. (b) Axial 7^-weighted slice spontaneously shows a slight increase of signal of the tumor. Note the displaced ventral matrix (arrowhead), the dorsal matrix (small arrows) and the bone erosion of the dorsal cortex (large arrow). (c) Axial postgadolinium 7^-weighted image shows a strong and homogeneous enhancement of the glomus tumor. (d) Magnetic resonance angiography confirms the high degree of vascularization of the tumour on the delayed sequence.

Perionychium

Figure 11.8

Solid form of glomus tumour. Axial post-gadolinium 7^-weighted image shows a tumour with a signal equal to the signal of the nail bed. The tumour is highlighted by its peripheral low-signal pseudocapsule (arrows) and the bone erosion (arrowheads).

Figure 11.8

Solid form of glomus tumour. Axial post-gadolinium 7^-weighted image shows a tumour with a signal equal to the signal of the nail bed. The tumour is highlighted by its peripheral low-signal pseudocapsule (arrows) and the bone erosion (arrowheads).

Subungial Wart With Bone Erosion

Figure 11.9

Mucoid type of glomus tumour. Sagittal ^-weighted image depicts a tumour with a high signal (arrows) and an internal septum (arrowhead).

Figure 11.9

Mucoid type of glomus tumour. Sagittal ^-weighted image depicts a tumour with a high signal (arrows) and an internal septum (arrowhead).

with a peripheral pseudocapsule (see Figure 11.8). This capsule is a reactional response of the surrounding connective tissue; it presents a low signal on all sequences, but is more visible on ^-weighted images or three-dimensional gradient echo images. In some cases the tumour limits are ill defined, and injection of gadolinium—particularly with MR angiography—may depict small foci of tumour extending into the nearby nail bed (Figure 11.11). Often in these cases, adhesions with the nail bed are noted during surgery. Local invasion of the capsule is debated; it has been reported on histological examinations in less than 2% of cases. It is certain that the risk of recurrence is high if some tumoral tissue is left in situ during surgery of these ill-defined lesions. The reported recurrence rate varies from 12% to 24%. Magnetic resonance imaging appears to be particularly helpful in cases of recurrent pain after surgery (Figure 11.12). Magnetic resonance angiography also is able to depict multiple glomus tumours in the hand or in the same finger tip. In these cases, MRI is essential for planning the surgical approach (Figure 11.13).

Figure 11.10

Mixed glomus tumour. Axial post-gadolinium three-dimensional gradient echo image shows heterogeneous enhancement of the tumour.

Figure 11.10

Mixed glomus tumour. Axial post-gadolinium three-dimensional gradient echo image shows heterogeneous enhancement of the tumour.

In most cases the tumour is located in the subungual area, in the supporting tissue of the nail bed or the matrix. These locations are the most difficult to depict with ultrasonography when the tumour is smaller than 3 mm. Usually the lesion is deep, close to the periosteum of the underlying phalanx. Often a cortical bone erosion is depicted on the axial slices although it was occult on radiographs. These axial slices are essential to distinguish the tumours on the median line from those of the lateral part of the nail bed, which sometimes extend into the pulp via the rima ungualum. The surgical approach is planned according to the size and location of the tumour. Lateral tumours may be excised by a lateral approach while the median type may require a transungual approach. Sagittal slices are essential to determine the relations between the tumour and the nail matrix. Unusually, the lesions may be located in the pulp or the posterior nail fold; in such cases, the contrast between healthy tissue and tumour is completely different because of the fatty tissue of the hypodermis surrounding the tumour. The low-signal tumour is spontaneously visible on T1-weighted images, surrounded by the high signal of fat. The tumour enhancement after injection of gadolinium is only visible with associated fat suppression (Figure 11.14).

Figure 11.11 Multiple glomus tumours. (a) Axial postgadolinium ^weighted slice depicts two tumours in the nail bed on

the midline (arrows) with bone erosions. (b) Magnetic resonance angiography shows multiple nodular enhancement in the nail bed (arrows).

Figure 11.12

Postoperative recurrent glomus tumour, (a) Axial post-gadolinium T1-weighted image faintly shows a recurrent tumour in the nail bed with a bone erosion (arrowhead). Note the artefacts (arrows) of the previous surgery on the lateral nail fold, (b) Magnetic resonance angiography

Figure 11.12

Postoperative recurrent glomus tumour, (a) Axial post-gadolinium T1-weighted image faintly shows a recurrent tumour in the nail bed with a bone erosion (arrowhead). Note the artefacts (arrows) of the previous surgery on the lateral nail fold, (b) Magnetic resonance angiography highlights the enhancement of the glomus tumour. Note the dark postoperative artefact (arrow) close to the tumour.

Perionychium

Figure 11.13

Multiple glomus tumours involving the third (arrow) and fourth (arrowhead) finger tips, seen on MR angiography.

Figure 11.13

Multiple glomus tumours involving the third (arrow) and fourth (arrowhead) finger tips, seen on MR angiography.

Perionychium

Figure 11.14

Glomus tumour seated in the pulp and the rima ungualum. Axial fat-suppressed post-gadolinium 7^-weighted image depicts the tumour enhancement (arrow) surrounded by the low signal of fat.

Figure 11.14

Glomus tumour seated in the pulp and the rima ungualum. Axial fat-suppressed post-gadolinium 7^-weighted image depicts the tumour enhancement (arrow) surrounded by the low signal of fat.

Glomus tumours are easily distinguished from other vascular lesions, such as venous haemangiomas and arteriovenous malformations, by their characteristic blood flow artefacts and vascular pedicles.

Other vascular tumours

Vascular tumours that involve the perionychium are mostly benign, except for Kaposi's sarcoma. The histological types are numerous, from the exceptional haemangioma of the nail bed to the capillary malformations present from birth. Radiographs can depict a mass in the soft tissues, phleboliths, and even a bone erosion with venous and arteriovenous malformations, or an epithelioid haemangiendothelioma. The bone may be primarily involved by a haemangioma (linear striations parallel to the shaft of the phalanx) or an aneurysmal bone cyst (expansive osteolytic lesion of the

Perionychium

Figure 11.15

Vascular malformation of the finger tip. Sagittal post-gadolinium T1-weighted image depicts a thickened nail bed invaded by a thrombosed (black arrow) and an enhanced (arrowhead) vascular malformation. Note the extension towards the pulp with numerous flow void artefacts (white arrows) due to high blood velocity.

Figure 11.15

Vascular malformation of the finger tip. Sagittal post-gadolinium T1-weighted image depicts a thickened nail bed invaded by a thrombosed (black arrow) and an enhanced (arrowhead) vascular malformation. Note the extension towards the pulp with numerous flow void artefacts (white arrows) due to high blood velocity.

phalanx). It is not possible to differentiate all these types of vascular lesions by MRI, but discrimination is improved with MR angiography. The vascular nature often is obvious with high-flow malformations (flow void artefacts) and low-flow lesions (very bright signal on T2-weighted images) (Figure 11.15). Manetic resonance imaging assesses the extension of the lesion into the soft tissues and MR angiography the angioarchitecture of the malformation and its relations with the digital collateral arteries and the venous plexus.

Mucoid cysts

Complementary imaging of mucoid cysts may seem irrelevant because the clinical diagnosis is easy; most of the cysts originate from the accessible posterior nail fold. However, the high

Perionychium

Figure 11.16

Mucoid cyst of the proximal nail fold and the pulp (arrows),

Figure 11.16

Mucoid cyst of the proximal nail fold and the pulp (arrows),

Sagittal 7^-weighted image; note the dorsal osteophyte of the phalangeal head (arrowhead), (b) Sagittal ^-weighted image. Note the intracystic septa (arrowheads).

recurrence rate despite numerous treatment possibilities may increase the interest in accurate preoperative imaging. High-resolution MRI can accurately analyse the relations between the cyst and the distal interphalangeal joint. Most of the cysts are solitary and located on the proximal nail fold. Their appearance is specific: thin, regular walls, low signal on ^weighted images and very high signal on ^-weighted images. Intracystic septa are best seen on ^-weighted images in 39% of cases (Figure 11.16). Injection of gadolinium shows early faint peripheral enhancement and with time the enhancement moves toward the centre of the cyst. This diffusion of contrast media may be compared to the intra-articular diffusion of gadolinium at the level of the knee through the synovium after intravenous injection of gadolinium. However, a true synovial membrane has not been found in digital cysts, apart from a possible peduncle. Magnetic resonance imaging is able to highlight satellite cysts or sagging multiloculated cysts (Figure 11.17). These latter forms may be difficult to detect clinically, unless the typical signs of swelling and discharge of a thick fluid from the proximal nail fold are found. In these infrequent

Perionychium
Mole Removal

Mole Removal

Moles, warts, and other unsightly irregularities of the skin can be bothersome and even embarrassing. They can be removed naturally... Removing Warts and Moles Naturally! If you have moles, warts, and other skin irregularities that you cannot cover up affecting the way you look, you can have them removed. Doctors can be extremely expensive. Learn the natural ways you can remove these irregularities in the comfort of your own home.

Get My Free Ebook


Responses

  • Gimja
    What is mucoid degeneration of the phalanges?
    7 years ago

Post a comment