Distal Phalanx Specific Pathology

Overview:

  • bone atrophy secondary to overlying soft tissue mass
  • post-traumatic ossified hematoma
  • bone cyst
  • fracture
  • osteomyelitis
  • DIPJ arthritis

Use of Imaging

Plain film radiography is the initial study of choice for further evaluation of pathology adjacent to or under the nail. Ultrasound may also be useful for soft tissue pathology. MRI can be beneficial when evaluating soft tissue masses in this location.

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DP Epidermoid Inclusion Cyst

DP Epidermoid Inclusion Cyst

DP view. A well-defined erosion (E) involves the medial aspects of the hallux distal phalangeal base and proximal metadiaphysis. It is bounded by a thin, well-defined sclerotic margin (arrow). Diagnosis: Pressure atrophy secondary to an overlying epidermoid inclusion cyst.

DP Pressure Atrophy

DP Pressure Atrophy

DP view. A large, well-defined erosion presents along the anterocentral aspect of the hallux distal phalangeal ungual tuberosity. Diagnosis: pressure atrophy secondary to an overlying soft tissue mass.

bone abscess

bone abscess

DP view. There is an oval-shaped (or, geographic) decreased density (c) in the center of the distal phalanx diaphysis that is surrounded by diffuse sclerosis (s). Other findings include osseous irregularity along the medial aspect of the diaphysis (arrow; "t" is the plantar-medial tubercle that varies in size). Diagnosis: this is the presentation of a bone abscess in the proper clinical setting. However, this particular bone cyst was not confirmed by biopsied; other differential diagnoses include post-trauma and tuberous sclerosis.

Fracture Ungual Tubersity

Fracture Ungual Tubersity

DP view. The anterolateral tip of the ungual tuberosity (f) is separated from the distal phalanx. The margins of these two bone segments are ill-defined (arrow). There is diffuse increased soft tissue nd volume involving the hallux. Diagnosis: fracture.

DP Osteomyelitis

DP Osteomyelitis

DP view. An ill-defined erosion (e) and/or lucency involves the anterolateral aspect of the ungual tuberosity. There is also increased soft tissue density throughout the tip of the toe. This patient had a chronic ingrown nail and paronychia; the findings described above strongly suggest osteomyelitis in the proper clinical setting; however, often the lab tests come back negative for infection. This would suggest that the findings are a result of chronic inflammation.

DP Osteomyelitis   Lateral Osteomeyelitis

DP Osteomyelitis   Lateral Osteomeyelitis

DP and lateral views. There is gross osteolysis of the entire distal phalanx except its base. Multiple ill-defined bone segments (sequestrum, arrows) are visible. Diagnosis: osteomyelitis.

diaphyseal fracture

diaphyseal fracture

Medial oblique view. A transversly oriented irregular (jagged) and ill-defined decreased density (arrows) runs across the distal phalanx proximal metadiaphysis. There is a localized increased soft tissue density dorsomedial to the hallux distal phalangeal base. There was a history of injury. Diagnosis: fracture.

non-union fracture

non-union fracture

DP view. An Increased soft tissue density and volume involve the entire distal half of the hallux. There also is a defect (d) along the distal-medial margin of the toe. Erosions or geographic lucent lesions (black arrows) are noted along the distal aspect of the ungual tuberosity. Additional findings involve the second toe and include increased soft tissue volume distally and diffuse sclerosis throughout the distal phalanx except for a curvilinear decreased density (white arrows) that runs across the diaphysis. Diagnoses: hallux ulcer with adjacent osteomyelitis or other inflammatory process, hallux distal phalanx; nonunion fracture of the second toe distal phalanx.

avulsion fracture

avulsion fracture

Lateral view. An ossicle (arrow) is seen along the superior aspect of the distal interphalangeal joint. There is a defect along the adjacent distal phalangeal base superiorly. The adjacent margins are somewhat ill defined in outline. Diagnosis: avulsion fracture.

osteoarthritis

osteoarthritis

DP view. There is irregular narrowing (arrow) of the fourth toe distal interphalangeal joint with subchondral sclerosis. Diagnosis: osteoarthritis.

enostosis

enostosis

DP view. A geographic, solid increased density is present along the medial aspect of the hallux distal phalangeal diaphysis (arrow). Diagnosis: enostosis (aka bone island).

Should a radiographic study be ordered for evaluation of a soft tissue mass?

One may believe that, since soft tissues are not imaged well, plain films of the foot and ankle should not be requested. However, in many cases radiographs are valuable in assessment because soft tissue masses may :

  • consist of calcifications or ossifications, which may prove valuable for differential diagnosis;
  • arise from a primary agressive bone tumor;
  • be infectious and invade adjacent bone;
  • cause pressure atrophy of adjacent bone that could weaken and fracture.
What are the best views to order?

Order DP and lateral views of the hallux. (If radiographs are being obtained only to assess the hallux distal phalanx, then views collimated to the hallux only should be requested. Using an appropriate kVp and mAs technique will also provide some visibility of the nail and adjacent soft tisue structures.) Choose an oblique view based upon where the suspected mass is located: if dorsomedial, order the medial oblique view; if dorsolateral, order the lateral oblique. If dorsal and central, an oblique is probably not necessary.

Related information, trivia & esoterica!

Psoriatic arthritis is associated with pitting of the nails. In these cases, there may be abnormal findings that involve the distal phalanx, such as "whiskering", ivory phalanx, and ungual tuberosity resorption.

Glomus tumors are common in the fingers but rare in the toes.

References:

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  2. Drape´ JL: Imaging of tumors of the nail unit. Clin Podiatr Med Surg 21 (2004) 493– 511
  3. Baran R, Richert, B: Common Nail Tumors. Dermatol Clin 24 (2006) 297–311
  4. Sapuan J, Paul, AG and Abdullah, S: Glomus Tumor in the Second Toe: A Clinical Insight. The Journal of Foot & Ankle Surgery 47(5): 483–486, 2008
  5. Lee DK: Distant Metastases to the Hallux in Nasopharyngeal Carcinoma. J Am Podiatr Med Assoc 98(3): 239-241, 2008
  6. Choi JJ, Murphey MD: Angiomatous Skeletal Lesions. Seminars in Musculoskeletal Radiology Vol 4(1):103-112, 2000
  7. Pontious J, Labovitz JM. Periungual fibromas associated with tuberous sclerosis. Int J Low Extrem Wounds 1997;4:19–23
  8. Glazebrook KN, Laundre BJ, Schiefer TK, Inwards CY: Imaging features of glomus tumors. Skeletal Radiol (2011) 40:855–862
  9. Mahoney LM, Scott R: Psoriatic Onychopachydermoperiostitis (POPP). J Am Podiatr Med Assoc 99(2): 140-143, 2009