AJR 2005; 185:174-175
© American Roentgen Ray Society
Radiologic-Pathologic Conference of Brooke Army Medical
Center |
Subungual Squamous Cell Carcinoma of the Finger
Liem T. Bui-Mansfield1,2,3,
Joseph P. Pulcini4 and
Stephen Rose5
1 Department of Radiology, Brooke Army Medical Center, San Antonio, TX
78234.
2 Department of Radiology, Uniformed Services University of the Health Sciences,
Bethesda, MD 20814-4799.
3 Department of Radiology, Wake Forest University School of Medicine, Medical
Center Blvd., Winston-Salem, NC 27157-1088.
4 Department of Pathology, Brooke Army Medical Center, San Antonio, TX
78234.
5 Department of Surgery, Orthopedic Service, Brooke Army Medical Center, San
Antonio, TX 78234.
Received November 21, 2004;
accepted after revision November 29, 2004.
The opinions and assertions contained herein are those of the authors and
should not be construed as official or as representing the opinions of the
Department of the Army or the Department of Defense.
Address correspondence to L. T. Bui-Mansfield
(liem_mansfield{at}hotmail.com).
A 53-year-old woman presented to a dermatologist with a subungual
mass in the right index finger. Radiographs revealed a subungual soft-tissue
mass that had eroded into the distal phalanx of the index finger. The
dermatologist performed a biopsy, revealing the diagnosis of squamous cell
carcinoma. The index finger was amputated.
The differential diagnosis of an erosive lesion in the distal phalanx
includes implantation dermoid cyst, subungual fibroma, glomus tumor, giant
cell tumor of tendon sheath, subungual squamous cell carcinoma, subungual
keratoacanthoma, and mucous cyst
[1].
Radiologically, subungual squamous cell carcinoma is almost
indistinguishable from subungual keratoacanthoma. Keratoacanthoma is a
localized endoexophytic growth of squamous epithelium with a characteristic
central keratin-filled crater. Keratoacanthomas may be locally destructive and
sometimes are associated with transformation to squamous cell carcinoma with
subsequent invasion. Some authors consider keratoacanthoma a subset of
squamous cell carcinoma [2];
however, keratoacanthomas more frequently undergo spontaneous involution, and
the larger consensus is that they are separate lesions with distinctive
behavior. The treatment of subungual keratoacanthoma is conservative, while
that of subungual squamous cell carcinoma is amputation.
Both subungual keratoacanthoma and squamous cell carcinoma may present with
pain, localized swelling, and inflammation. Patients with subungual squamous
cell carcinoma tend to be older (seventh decade peak) than those with
keratoacanthoma (fifth decade peak)
[1-4].
Squamous cell carcinoma grows slowly and often is mistaken for chronic
inflammation. In contrast, subungual keratoacanthoma grows rapidly,
proliferating to an obvious 1- to 2-cm mass within several weeks to months;
then generally stabilizes and later spontaneously involutes, leaving a small
pitted scar [1]. Eighty-four
percent of subungual squamous cell carcinomas occur in the fingers, the
remaining in the toes. The majority of subungual squamous cell carcinoma in
the fingers occurs in the thumb (44%); and those in the toes affect the great
toe predominately (64%) [3,
4].
Predisposing factors for subungual squamous cell carcinoma include chronic
paronychia, trauma, congenital ectodermal dysplasia, radiation exposure, and
previous human papillomavirus (HPV) infection
[3,
4]. In one study, HPV DNA was
present in 80% of cases of subungual squamous cell carcinoma by dot-blot
analysis of frozen tissue and 60% were related to HPV 16
[3]. Although the cause of
keratoacanthoma is unknown, trauma, coal tars, occupational chemical
carcinogens, eczema, psoriasis, atopic dermatitis, and xeroderma pigmentosum
have been implicated. Sunlight also is an important pathogenic factor, with
white persons most often affected, and the incidence of keratoacanthoma is
increased in areas with greatest exposure to the sun
[1].
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Fig. 1C —53-year-old woman with subungual squamous cell carcinoma of
index finger. Photomicrograph shows deep margin of subungual squamous cell
carcinoma (S) containing atypical squamous epithelium with periosteal tissue
(P). (H and E, x100)
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Subungual keratoacanthoma usually has the radiographic appearance of a
crescent-shaped lytic defect without sclerosis or periosteal reaction. Bone
involvement is seen in fewer than 20% of cases of subungual squamous cell
carcinoma, and metastases are even rarer (1.7%)
[3,
4].
References
- Levy DW, Bonakdarpour A, Putong PB, Mesgarzadeh M, Betz RR.
Subungual keratoacanthoma. Skeletal Radiol1985; 13:287
-290[Medline]
- Choonhakarn C, Ackerman AB. Keratoacanthomas: a new classification
based on morphologic findings and on anatomic site.
Dermatopathology: Practical and Conceptual2001; 7:7
-16
- Guitart J, Bergfeld WF, Tuthill RJ, Tubbs RR, Zienowicz R, Fleegler
EJ. Squamous cell carcinoma of the nail bed: a clinicopathological study of 12
cases. Br J Dermatol1990; 123:215
-222[Medline]
- Attiyeh FF, Shah J, Booher RJ, Knapper WH. Subungual squamous cell
carcinoma. JAMA1979; 241:262
-263[Abstract]
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