Treating A Pigmented, Slightly Pruritic Nodule

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Key Questions to Consider

1. What essential question does one still need to ask to help make the diagnosis?

2. What is the tentative diagnosis?

3. Can you list at least three differential diagnoses?

4. In regard to the differential diagnosis, what features of this condition differentiate it from other conditions?

5. What is the suitable treatment of this condition?

Answering The Key Diagnostic Questions

1. Do you recall any previous injury, insect bite or other problems in the area of the lesion?

2. The most likely diagnosis is a solitary dermatofibroma
(fibrohistiocytoma).

3. The differential diagnosis includes but is not limited to epidermal cyst, keloid scar, prurigo nodularis, basal cell carcinoma, dermatofibrosarcoma protuberans, foreign body granuloma and insect bites and stings.

4. The condition is characterized by skin lesions that are papular or nodular, firm, raised, round-to-oval and pigmented. They usually retract beneath the skin surface when one squeezes them from either side. This is called the Fitzpatrick Dimple Sign.

5. Treatment is usually not necessary but when these lesions are symptomatic or problematic, one needs to remove them surgically. However, since they are deep, this usually leaves a visible hyperpigmented scar. Cryotherapy may eliminate much of the color of the lesion. It may also flatten and reduce the size of the lesion. Cortisone injections using 4 mg/mL of dexamethasone sodium phosphate may also be helpful.

34
Author(s): 
By G.“Dock” Dockery, DPM, FACFAS

Injections with intralesional corticosteroids may decrease the size and color of lesions. In many cases, the steroid will make them softer. Steroid injections are not considered to be highly successful and have some potential complications of atrophy, discoloration and/or telangiectasia. Some physicians have stopped recommending this approach. Cryosurgery is also useful in flattening and decreasing the color of lesions. This approach does not have the potential side effects of steroid injections.

Since dermatofibromas are deep lesions with widened bases, simple excision of the lesion may result in unsightly, thick and dark scars. Recurrences are common. Wide excision of the lesion and complete removal of the deep portions of the mass are necessary to prevent return of the lesion. One may subsequently close the resultant defect with a variety of reciprocal flaps used for closing circular defects or with a single-lobed flap. One should submit all removed specimens for dermatopathology confirmation of the diagnosis of dermatofibroma.

Dr. Dockery is a Fellow of the American College of Foot and Ankle Surgeons, and the American Society of Podiatric Dermatology. He is board certified in foot and ankle surgery.

Dr. Dockery is the Chairman of the Board and Director of Scientific Affairs for the Northwest Podiatric Foundation for Education & Research, USA. Dr. Dockery is the author of Cutaneous Disorders of the Lower Extremity (Saunders, 1997) and Lower Extremity Soft Tissue & Cutaneous Plastic Surgery (Elsevier Sciences, 2006).




References:

Suggested Reading
1. Dockery GL. Single lobed rotation flaps. J Am Podiatr Med Assoc. 85:36-40, 1995.
2. Dockery GL. Benign tumors, cysts, and lesions, ch. 13, in: Cutaneous Disorders of the Lower Extremity. W.B. Saunders Co., Philadelphia, pp. 204-205, 1997.
3. Dockery GL. Advancement and rotational flaps. Ch 15, pp 129-146, In: Dockery GL, Crawford ME (eds): Lower Extremity Soft Tissue & Cutaneous Plastic Surgery, Elsevier Science Limited (Saunders), Oxford-Philadelphia, 2006.
4. Dockery GL, Schroeder S. How to diagnose and treat insect bites and stings, Podiatry Today. 19(6):90-98, 2006.
5. Fitzpatrick TB, Gilchrest BD. Dimple sign to differentiate benign from malignant pigmented cutaneous lesions. N Engl J Med, 296:1518, 1977.
6. Hendi A, Jukie DM, Kress DW, Brodland DG. Atrophic dermatofibroma: a case report and review of the literature. Dermatol Surg. 28(11):1085-1087, 2002.
7. Kovach BT, Boyd AS. Melanoma associated with a dermatofibroma. J Cutan Pathol. 34(5):420-422, 2007.
8. Lanigan SW, Robinson TW. Cryotherapy for dermatofibromas. Clisn Exp Dermatol, 12:121-123, 1987.
9. Laughlin CL, Carrington PR. Deep penetrating dermatofibroma. Dermatol Surg. 24(5):592-594, 1998.
10. Naversen DN, Trask DM, Watson FH, Burket JM. Painful tumors of the skin: “LEND AN EGG.” J Am Acad Dermatol. 28:298-300, 1993.
11. Pierson JC, Pierson DM. Dermatofibroma. eMedicine, July 2007. Available at: http://www.emedicine.com/DERM/topic96.htm
12. Requena L, Farina MC, Fuente C, Pique E, et. al. Giant dermatofibroma. A little-known clinical variant of dermatofibroma. J Am Acad Dermatol. 305:714-718, 1994.
13. Zelger B, Zelger BG, Burgdorf WH. Dermatofibroma- a critical evaluation. Int J Surg Pathol. 12(4):333-334, 2004.

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