AJR 2005; 184:S110-S111
© American Roentgen Ray Society
Primary Squamous Cell Carcinoma: An Incidental Toe Mass
Stavroula J. Theodorou1,
Daphne J. Theodorou1,
Susan J. Bona2 and
Shella Farooki3
1 Department of Radiology, University of California School of Medicine, San
Diego, CA.
2 Department of Pathology, The Ohio State University Medical Center, Columbus,
OH.
3 Department of Radiology, The Ohio State University Medical Center, Columbus,
OH.
Received January 5, 2004;
accepted after revision April 3, 2004.
Address correspondence to D. J. Theodorou, 13 Papadopoulos St., Ioannina,
45444 Greece.
Introduction
Nonmelanoma skin cancer is the most common cancer in the United
States [1]. Approximately 80%
of the nonmelanoma skin cancers are basal cell carcinomas, and 20% are
squamous cell carcinomas. Although most cases of squamous cell carcinomas of
the skin are curable, some tumors may recur or metastasize. We describe the
MRI findings of the toe in a patient with primary squamous cell carcinoma and
correlate them with the histopathologic findings. To our knowledge, this is
the first case of primary squamous cell carcinoma of the foot studied with MRI
and histopathologic correlation.
Case Report
A 44-year-old woman presented with a 3-week history of intermittent,
left-sided chest pain and exertional dyspnea. The patient was a heavy smoker
(58 pack/year history). At the time of presentation, the patient complained
incidentally of a soft-tissue mass in her right fifth toe that had been
present for more than 15 years. In the previous 4 years, the mass had been
slowly enlarging. The patient had recently noticed pain, ulceration, brown
purulent discharge, and a foul smell from the mass.
A workup for coronary artery disease was negative. Physical examination of
the right foot showed an ulcerated, fungating, painful 5-cm mass of the fifth
digit. The patient was afebrile and a complete blood count was remarkable for
a WBC of 11.8 x 109/L. Radiographs of the right foot showed
no osseous abnormalities. A soft-tissue mass with no evidence of calcified or
ossified matrix was present in the lateral aspect of the fifth toe. MR images
of the right foot showed a soft-tissue mass measuring 4.5 x 2.5 x
2.8 cm in the dorsal, lateral, and plantar aspect of the fifth digit with
homogeneously low T1-weighted and intermediate T2-weighted signal intensity
(Figs. 1A and
1D). Abnormally high signal
intensity in the mass was seen on the STIR sequences
(Fig. 1B). After IV
administration of a gadolinium-containing contrast medium, the mass showed
heterogeneous striated enhancement (Fig.
1C). There was minimal increased intramedullary signal intensity
consistent with adjacent bone marrow edema. The mass was considered to be of a
soft-tissue origin. Because the tumor was in close proximity to the nail bed,
it was difficult to exclude involvement of this structure.
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Fig. 1A. —44-year-old woman with painful soft-tissue mass in right
fifth toe. Axial T1-weighted (TR/TE, 650/15) (A) and inversion recovery
(4,820/25; TI = 180 msec) (B) MR images show abnormally low and high
signal intensity, respectively, in soft-tissue mass of right fifth toe
(arrow).
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Fig. 1D. —44-year-old woman with painful soft-tissue mass in right
fifth toe. Coronal T2-weighted MR image (4,120/78) shows large mass of
heterogeneous intermediate signal intensity in right fifth toe
(arrow).
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Fig. 1B. —44-year-old woman with painful soft-tissue mass in right
fifth toe. Axial T1-weighted (TR/TE, 650/15) (A) and inversion recovery
(4,820/25; TI = 180 msec) (B) MR images show abnormally low and high
signal intensity, respectively, in soft-tissue mass of right fifth toe
(arrow).
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Fig. 1C. —44-year-old woman with painful soft-tissue mass in right
fifth toe. Coronal T1-weighted MR image (650/20) with fat saturation after IV
gadolinium administration reveals enhancement of soft-tissue mass in a
striated pattern.
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Surgical treatment consisted of amputation of the fifth toe. A friable
soft-tissue mass measuring 5 x 5.5 x 1 cm was removed. The mass
had invaded the nail bed but not the underlying bone. The surgical margins
were free of tumor. Histopathologic examination of the amputated fifth toe
revealed a florid proliferation of squamous epithelial cells showing low-grade
cytologic atypia and keratinization with infiltration of the dermis (Figs.
1E and
1F). The final pathologic
diagnosis was invasive, well-differentiated, primary squamous cell carcinoma
of the toe—a common cutaneous malignancy unusual in this anatomic
location.
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Fig. 1E. —44-year-old woman with painful soft-tissue mass in right
fifth toe. Photomicrograph of histopathologic specimen at low power reveals
normal dermis and epidermis (left) and invasive squamous cell carcinoma
(right). Note infiltration of tumor into deep dermis (arrow). (H and
E, x2)
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Fig. 1F. —44-year-old woman with painful soft-tissue mass in right
fifth toe. Photomicrograph at medium power shows infiltrating islands of
well-differentiated neoplasm and squamous epithelium within dermis. Foci of
keratin are also seen (thick arrow). (H and E, x10)
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Discussion
Squamous cell carcinoma of the skin is the second most common cancer that
affects Caucasians, with 200,000 new diagnoses each year in the United States
[1]. Metastatic disease is
uncommon, with an overall rate of 2%, although the incidence can be higher for
primary tumors in certain anatomic locations
[2]. Squamous cell carcinoma
originates from the squamous epithelium of the surface epidermis and may show
varying degrees of differentiation and keratinization
[2]. The clinical appearance is
variable, and the tumor may present as a skin-colored, red, or brown nodule
with or without scaling, a focus of induration, an ulcerated lesion, plaque,
or an exophytic cauliflower-like growth
[2]. Primary squamous cell
carcinoma may grow slowly or rapidly with invasion of the neighboring
structures. Although the MRI appearance of verrucous carcinoma, a rare subtype
of locally invasive squamous cell carcinoma of the foot, has been reported
[3], our case is the first to
describe the MRI findings of primary squamous cell carcinoma (nonverrucous, or
the usual type) of the foot.
The importance of this case from a diagnostic-imaging perspective is the
presentation of a soft-tissue neoplasm unfamiliar to many radiologists.
Differential diagnostic considerations for squamous cell carcinoma of skin
include keratoacanthoma, basal cell carcinoma, verrucous carcinoma, deep
mycosis, eccrine poroma, sweat gland carcinoma, amelanotic melanoma, pyogenic
granuloma, reactive epidermal hyperplasias overlying sites of infection,
chronic mechanical trauma changes, and cutaneous Hodgkin's disease. Although
the MRI appearance of squamous cell carcinoma of skin may be nonspecific,
placing the MRI findings in clinical context and assessment of histopathologic
findings is helpful for establishing the correct diagnosis. MRI helps to
determine the presence and extent of disease in the skin, surrounding soft
tissue, and subjacent bone, and therefore aids in surgical planning. Based on
the experience with this case, the presence of a soft-tissue mass in the foot
exhibiting characteristics of a chronic inflammatory process associated with
new pain or recent ulceration warrants diagnostic imaging, biopsy, or both to
avoid a misdiagnosis of malignancy. Given the potential for local destruction
and the potential risk, albeit small, for metastasis with squamous cell
carcinoma of the skin, this entity should be considered in the differential
diagnosis of soft-tissue masses in the foot.
References
- Alam M, Ratner D. Cutaneous squamous cell carcinoma. N
Engl J Med 2001;344:975
-983[Free Full Text]
- Barnhill RL. Tumors of the epidermis. In: Barnhill RL, ed.
Textbook of dermatopathology. New York, NY: McGraw
Hill, 1998: 521-525
- Bhushan M, Ferguson J, Hutchinson C, Muston H. Carcinoma
cuniculatum of the foot assessed by magnetic resonance scanning.
Clin Exp Dermatol2001; 26:419
-422[Medline]
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Introduction
Case Report
