CORRECT DIAGNOSIS:
Prurigo Nodularis
DISCUSSION:
Prurigo nodularis is a rare disease. It is considered as a nodular form of Lichen Simplex Chronicus. The true cause of prurigo nodularis is unknown. This disease may present as few to as many as 200+ nodules randomly distributed on arms and legs, especially the extensor surface. The lesions are created by repeated scratching of the skin. They present usually as dome-shaped lesions of 1-2 cm in diameter.
Most patients with the disease are often middle-aged to elderly. Lesions may demonstrate excoriation with flat, umbilicated, or crusted tops. Other differential diagnoses to consider include xanthoma, insect bites, keratoacanthoma, molluscum contangiosum, and squamous cell carcinoma. Skin biopsies may be indicated to exclude squamous cell carcinoma for these patients.
TREATMENT:
This patient was treated with an oral antihistamine (Atarax) to break the itch-scratch cycle. In addition, the patient received cryosurgery to the lesions with clinical improvements. Some other possible treatments include intralesional steroid injection – may be beneficial for some patients – and excision.
REFERENCES:
Berger, T. G., Hoffman, C., & Thieberg, M. D. (1995). Prurigo nodularis and photosensitivity in AIDS: Treatment with thalidomide. Journal of the American Academy of Dermatology, 33(5 Pt 1), 837–838. https://doi.org/10.1016/S0190-9622(95)90041-8 [Medline]
Meyers, L. N. (1989). Use of occlusive membrane in the treatment of prurigo nodularis [Letter]. International Journal of Dermatology, 28(4), 275–276. https://doi.org/10.1111/j.1365-4362.1989.tb02287.x
Perez, G. L., Peters, M. S., & Reda, A. M. (1993). Mast cells, neutrophils, and eosinophils in prurigo nodularis. Archives of Dermatology, 129(7), 861–865. https://doi.org/10.1001/archderm.129.7.861
Stoll, D. M., Fields, J. P., & King, L. E., Jr. (1983). Treatment of prurigo nodularis: Use of cryosurgery and intralesional steroids plus lidocaine. Journal of Dermatologic Surgery and Oncology, 9(11), 922. https://doi.org/10.1111/j.1524-4725.1983.tb02983.x
Ferrandiz, C., Carrascosa, J. M., & Just, M. (1997). Sequential combined therapy with thalidomide and narrow-band (TL01) UVB in the treatment of prurigo nodularis. Dermatology, 195(4), 359–361. https://doi.org/10.1159/000246889
Waldinger, T. P., Wong, R. C., & Taylor, W. B. (1984). Cryotherapy improves prurigo nodularis. Archives of Dermatology, 120(12), 1598–1600. https://doi.org/10.1001/archderm.120.12.1598
