PMC4359473_01
Photographs depicting the clinical phenotype. A. Dactylitis of the right fourth finger. B. Dactylitis of left fifth toe. C. Representative skin findings, here an annular plaque from right forearm characterized by erythema and overlying silvery scale, consistent with psoriasis. D. Scalp biopsy showing psoriasiform dermatitis, characterized by hyperkeratosis, parakeratosis, and neutrophils within the stratum corneum and spinous layer (hematoxylin and eosin, original magnification, 400x).
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Fig1
At age 14, shortly after completing a course of cyclophosphamide and a trip to Central America, she presented with atraumatic fusiform swelling and tenderness of the right fourth finger and left fifth toe (Figure 1A and B). Skin examination revealed white, scaling, erythematous plaques on the knuckles (Figure 1A), frontal and occipital scalp, and bilateral dorsal forearms (Figure 1C). A scalp biopsy showed psoriasiform dermatitis (Figure 1D), supporting the clinical diagnosis of psoriasis.
PMC4359473_02
Radiographic evaluation of dactylitis. A. Radiograph of right hand (dorsal view) demonstrating diffuse swelling around PIP joint of right fourth digit, indicated by arrow. B. Radiograph of left fifth toe (oblique view) and C. Radiograph of the left fifth toe (dorsal view), both illustrating soft tissue swelling of left fifth toe, indicated by arrow. Subcutaneous calcifications related to the patient's juvenile dermatomyositis are also evident.
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Fig2
Radiographs of the right hand and left foot showed soft tissue swelling of the right fourth digit and left fifth toe, without erosions or periosteal reaction (Figure 2A-C).
Magnetic resonance imaging evaluation of dactylitis. A. Coronal short tau inversion recovery (STIR), B. sagittal T2 with fat suppression, and C-F. axial T2 with fat suppression of the left fifth toe, proximal to distal sequences, demonstrating increased signal and gadolinium enhancement at the local entheses without associated tendonitis or synovitis.
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Fig3
Magnetic resonance imaging studies of the left fifth toe revealed swelling and contrast enhancement at the flexor tendon insertion with associated bone marrow edema, consistent with enthesitis, in the absence of either synovitis or tenosynovitis (Figure 3).
Morphologic evaluation of dactylitis. Both the affected finger and toe showed tenosynovial tissue with prominent vascularity and excess myxoid extracellular matrix (A, finger, original magnification, 100x); additionally, fibrocartilage showed a prominent myxoid component (B, toe, original magnification, 200x; C, toe, original magnification, 400x), areas of binucleation (D, toe, original magnification, 400x), and focal hypocellularity and coagulative necrosis (E, finger, original magnification, 400x). Fibrinous synovitis was also seen (F, finger, original magnification, 400x).
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Fig4
Histologic examination of both the toe and finger showed hypervascular tenosynovium (Figure 4).
Characterization of cellular inflammation. Hypervascular tenosynovium showing perivascular inflammation consisting predominantly of T cells (finger; A, hematoxylin and eosin; B, CD3 immunostain; original magnification, 400x). In areas where myxoid matrix expands fibrovascular tissue containing densely collagenized tendon-like fibers, mast cells are regularly interspersed (finger; C, hematoxylin and eosin; D, CD117 immunostain; original magnification, 400x).
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Fig5
Cellular inflammation (Figure 5) was mild in the toe and moderate in the finger, consisting predominantly of CD3-positive, CD5-positive, and CD4-positive T cells in both specimens, with rare CD8-positive cells.
PMC4359473_03