 |
|
Erythematous Nodule on the Nail Bed
Sharon Horton, MD;
Richard Mizuguchi, MD;
Ali Moiin, MD;
Ken Hashimoto, MD
Arch Fam Med. 2000;9:410-411.
REPORT OF A CASE
A 32-year-old white woman presented with a 2-year history of nail loss. She initially had noted a "small bump" on the corner of her right thumbnail. In time, the bump grew larger and split the nail, and, finally, a portion of the right thumbnail fell off. Occasionally, the patient experienced pain in the affected area of her thumb. Her medical history was noncontributory.
Cutaneous examination revealed a 7-mm erythematous nodule located on the lateral aspect of the right thumb, with the loss of one third of the lateral nail plate (Figure 1). An x-ray film of the thumb showed no evidence of bone abnormality. A biopsy specimen was obtained (Figure 2).
What is your diagnosis?
From Wayne State University, Detroit, Mich.
Diagnosis and Discussion: Amelanotic Subungual Melanoma
HISTOPATHOLOGIC FINDINGS AND CLINICAL COURSE
The surface epithelium was irregularly acanthotic, with extensive proliferation of atypical melanocytic cells at the dermoepidermal junction, and there were foci of junctional nest formation. Also, nests of elongated, spindle-shaped melanocytic cells extended from the dermoepidermal junction to the reticular dermis. Immunohistochemical studies revealed strong S100 protein expression of the tumor cells.
The patient was treated with amputation at the proximal interphalangeal joint of the thumb and has been without recurrence or metastasis during 1 year of follow-up.
DISCUSSION
Acral lentiginous melanoma is the most common form of melanoma in dark-skinned persons; however, it occurs infrequently among whites.1 It may involve the palms, soles, or nail bed. When it involves the nail bed, it is referred to as subungual melanoma. In 1886, Hutchinson2 first described subungual melanoma and initially termed it melanotic whitlow, because it often resembled an infection. In fact, the clinical differential diagnosis includes chronic paronychia and onychomycosis as well as subungual hematoma, pyogenic granuloma, and glomus tumor. Subungual melanoma is rare, accounting for only 1% to 3% of all cases of melanoma.3
Often, an important clue to the diagnosis of subungual melanoma is Hutchinson sign, which is characterized by extension of brown-black pigment from the nail bed, matrix, and nail plate onto the adjacent cuticle and proximal and/or lateral nail folds.4 The absence of periungual pigmentation does not preclude the diagnosis of subungual melanoma. Although there have been reports of amelanotic melanoma of the nail bed,5 the actual incidence is unknown and has never been reported in the literature.
In reviews of subungual melanoma, the median age of patients is 59 years.2, 6 There is a slight increase in prevalence among men (male-female ratio, 1.6:1.0).6 Reports differ regarding the incidence of lesions on the hands vs the feet. The lesions are predominantly located on the thumb or the great toe.2, 6 Also, ulceration and nail destruction are common, affecting more than 50% of patients with subungual melanoma.6
The prognosis of malignant melanoma of the nail is poor because most lesions are at an advanced stage at the time of diagnosis.7 Approximately 75% of primary tumors have been found to be more than 1.5 mm thick, with 61% invading to level IV or V.6 As with all types of melanoma, there is a strong relationship between increasing tumor thickness and decreasing survival time.
A study regarding prognostic factors in patients with subungual melanoma found 6 factors that greatly affect patient survival, and as suspected, tumor thickness and stage at presentation are the most important. The presence of ulceration and bone invasion also adversely affect survival. DNA studies show that a high aneuploid fraction and a low S-phase fraction also indicate a worse prognosis.6
Therapeutic management consists of complete excision of the tumor. The level of amputation has been debated; however, as long as clear margins are obtained, conservative levels of amputation are safe, do not adversely affect overall survival, and maximize functional capacity.6
AUTHOR INFORMATION
Selected from Arch Dermatol. 1999;135:1115. Off-Center Fold.
REFERENCES
|
1. Ridgeway C, Hieken T, Ronan S, et al. Acral lentiginous melanoma. Arch Surg. 1995;130:88-92.
FREE FULL TEXT
2. Hutchinson J. Melanosis is often not black: melanotic whitlow. BMJ. 1886;1:491.
FREE FULL TEXT
3. Finley III RK, Driscoll DL, Blumenson LE, Karakousis CP. Subungual melanoma: an eighteen-year review. Surgery. 1994;116:96-100.
ISI
| PUBMED
4. Boran T, Kechijian P. Hutchinson's sign: a reappraisal. J Am Acad Deramatol. 1996;34:87-90.
FULL TEXT
|
ISI
| PUBMED
5. Hara M, Karo T, Tagami H. Amelanotic acral melanoma masquerading as fibrous histiocytic tumors. Acta Derm Venereol. 1993;73:283-285.
ISI
| PUBMED
6. Heaton K, el-Naggar A, Erisign L, et al. Surgical management and prognostic factors in patients with subungual melanoma. Ann Surg. 1994;219:197-204.
ISI
| PUBMED
7. Ishihara Y, Matsumoto K, Kawachi S, et al. Detection of early lesions of "ungual" malignant melanoma. Int J Dermatol. 1993;32:44-47.
FULL TEXT
|
ISI
| PUBMED
|
