Cases of Interest: Finger Painting

by Bruce D. Ragsdale, MD
Western Dermatopathology

A 49-year-old male had an injury 2 decades ago and recently developed nodular swelling of the distal index finger (Fig. 1). Procedure: Left index finger debridement. The resultant pink-tan 17 x 14 x 11-mm specimen was mottled by white chalky deposits. Microscopically, multinucleated giant cells contained pale yellow-green translucent material that was weakly birefringent (Fig. 2). Mononuclear histiocytes contained finely particulate material that appeared jet black under conventional transillumination (Fig 3).

Your diagnosis is:

  • Gout
  • Calcium pyrophosphate deposition disease
  • Paint
  • Pigmented giant cell tumor of tendon sheath
  • Metastatic melanoma

Diagnosis: Granulomatous inflammatory reaction to paint decades post paint gun injury

Viewed in transmitted light, either in the H&E slide (Fig. 3 on prior page) or an unstained slide (Fig. 4), the material appears dark because it is obstructing the light coming from the condenser below. But the particulate foreign material is white when viewed in incident light, photographed by turning off the microscope light and illuminated merely from window light (Fig. 5); this and the "chalky" gross specimen appearance indicates the color of the original injected paint was white.

Upon questioning the clinician, it was learned that the injury 20 years prior was a blast from a paint gun that inflated part of the hand. Submitted without relevant history, tissue like this has been mistaken for giant cell tumor of tendon sheath (6).

The number of high-pressure injection injuries due to paint guns has grown since the 43 reported in the English literature as of 1985 (7). The airless paint gun delivers paint at pressures approximating 3,000 psi. Paint accidently injected into the skin under this pressure causes a devastating injury, a result of the paint material, the level of bacterial contamination, and the pressure at which the paint is delivered (3). The real extent of damage in high-pressure injection injuries is hidden behind a small and frequently painless punctiform skin lesion on the finger or the hand (8). The degree of toxicity of the material, the amount injected, and early adequate treatment are the three most important factors in determining the final result. Paint is the more toxic agent compared to grease from grease-gun injuries and causes an extreme amount of tissue inflammation (1, 9). Paint-gun injuries with latex paint appear to be associated with an outcome that is superior to the poor outcome traditionally associated with oil-based paints (5).

The time interval between injury and treatment seems a critical determinant of outcome. Early debridement of the injected material gives the best functional result. Immediate antibiotic treatment is indicated in all patients. Decompression of the closed vascular compartments of the hand must be begun immediately to release the underlying tissue distended by the injected paint. Some studies indicate that steroids limit the severity of inflammatory response (3). In spite of early surgical debridement, some of these injuries, most commonly with highly toxic agents, progress to eventual amputation (2) and have been an unusual source of lead poisoning (4).

Technical Notes

  1. A "soap box" of mine is that in absence of a clinical photo, radiologic images more than suffice to illustrate an interesting case and frequently show more informative details than an external view.
  2. If you have a digital camera mounted above your scope, turning off the lamp converts it to a powerful dissecting scope (Fig. 5). Try it.

References

  1. Atkinson RE. Injection injuries of the hand: Caveat doctor. Hawaii Med J. 1989 Sep;48(9):364-6, 395.
  2. Booth CM. High pressure paint gun injuries. Br Med J. 1977 Nov 19;2(6098):1333-5.
  3. Edlich RF, et al. Airless paint gun injuries: an update. JACEP. 1978 Nov;7(11):397-400.
  4. Lilis R, et al. Paint spray gun injury of the hand. Report of an unusual source of lead poisoning. JAMA. 1981 Sep 11;246(11):1233-5.
  5. Lozano-Calderón SA, et al. Latex Paint-gun Injuries of the Hand: Are the Outcomes Better? Hand (N Y). 2008 Dec;3(4):340-5. Epub 2008 May 28.
  6. Stefanato CM, Turner MS, Bhawan J. High-pressure paint-gun injury of the finger simulating giant cell tumor of tendon sheath. J Cutan Pathol. 2005 Feb;32(2):179-83.