ARTICLE
A 72-year-old Japanese man presented with a 6-month history of painful
nodules on the left sole in November 1995. Physical examination disclosed
four hemorrhagic bullae-like nodules, 15 x 15 mm in diameter on the left
sole (Fig. 1). Only a
small quantity of bloody fluid was taken by aspiration. He had undergone
no preceding trauma, such as burn or cryotherapy on the lesions. His left
kidney had been resected in October 1995 because of renal cell carcinoma.
A biopsy specimen was taken from a lesion for routine histological analysis
(Fig. 2).
Skin metastasis of
renal cell carcinoma
A biopsy specimen from the nodule showed a honeycomb-like or adenoid
structure (Fig. 2) consisting
of large cells with clear cytoplasm and cells with granular eosinophilic
cytoplasm. The substratum was fibrous and highly vascular. The nuclei
of the tumor cells were atypical, with indentations and prominent nucleoli.
Similar histological findings were observed in the primary tumor of the
renal cell carcinoma of the left kidney. The cytoplasm of the clear cells
was full of PAS-positive granules before, but not after, digestion with
diastase. Immunohistochemical staining was positive for keratin and vimentin
while negative for EMA and CEA.
In January 1996, the patient died of brain metastasis
from the renal cell carcinoma which had been revealed on CT after our
examination. No evidence of any other metastasis was revealed.
Discussion
Renal cell carcinoma (RCC) accounts for 2 to 3% of malignant tumors
[1]. The skin is the seventh most common site of metastatic involvement
of RCC. The reported incidence of cutaneous metastases in patients with
RCC varies from 2.8 to 6.8% [1, 2]. Cutaneous metastasis may be seen anywhere
on the body, although a predilection for the scalp has been described
by many authors [1-4]. Pedal skin metastasis of RCC is so rare that, to
the best of our knowledge, only one case of pedal skin metastasis of RCC
has been reported to date [5].
Previous reports indicated that only in a minority
of patients are cutaneous lesions seen before the identification of RCC
[1, 6], however, a recent report suggested that metastasis to the skin
from RCC as first evidence of the disease may not be as rare as the literature
describes [2]. In case of cutaneous metastasis seen before the identification
of RCC, differential diagnoses, which consist of sebaceous carcinoma,
sweat gland tumor, vascular tumor or malignant melanoma with balloon cells,
should be considered. Kouroupakis et al. [2] reported that positive
immunohistochemical staining with both keratin and vimentin antibodies
make the diagnosis certain. Haruki et al. [7] reported that an
electron micoscopy approach may provide a clue for diagnosis of cutaneous
metastasis of RCC. Although we have not made an electron microscopic study
in this case, positive results with keratin and vimentin antibodies were
obtained as described above.
Although most of the previous reports described that cutaneous metastasis
of RCC usually presents as a raised, soft, well-circumscribed, intracutaneous
nodule [7], our case presented hemorrhagic bullae-like lesions. We speculate
that the hemorrhagic aspect of the lesions was due to the highly vascular
stroma of the metastases and the site i.e. the sole, which has
a thick, horny layer.
REFERENCES
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1991; 18: 218-24.
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