Giant cell tumor of the distal phalanx of the foot

ARTICLE

Giant cell tumor of the distal phalanx of the foot

Auteur(s) : Yasuhiro FUJISAWA, Takenori TAKAHASHI, Yasuhiro KAWACHI, Fujio OTSUKA

Department of Dermatology, University of Tsukuba
1-1-1 Tennodai, Tsukuba City, Ibaraki Prefecture, Japan 305-8575
Fax: 81-29-853-3217
<c0530312@kiban.md.tsukuba.ac.jp>W>

Giant cell tumor of the bone (GCTB) is a rare benign bone tumor, accounting for approximately 4% of all primary bone neoplasms [1]. It typically involves the long bones in young adults; it is very rare in the phalanges of the foot, with only six cases reported to date [2]. To our knowledge, there have been no previous case reports of GCTB in the distal phalanx of the foot providing detailed clinical information.
It is difficult to make a definitive diagnosis of GCTB in the phalanx due to the rarity of this type of tumor. The clinical appearance of GCTB is of no diagnostic significance, with only swelling and tenderness mentioned in previous reports [2, 3]. A definitive diagnosis of GCTB should be made only after detailed pathological examination of the whole tumor because radiological analysis and examination of biopsy specimens are insufficient to allow differential diagnosis from other giant cell-containing tumors. Complete block resection of the tumor or amputation is recommended because GCTB of the small bones recurs in 75% of patients treated by simple curettage [4]. Furthermore, a whole bone survey is recommended to check for other potential lesions due to the high incidence (24%) of multicentric GCTB tumors in small bones [5].
A 40-year-old woman was referred to Tsukuba University Hospital on December 9, 2004, with a 2-year history of evident swelling of the distal right second toe. The toe showed marked swelling without tenderness. The nail matrix was enlarged without destruction, indicating a slow growing tumor (figure 1A). The results of routine laboratory examinations, including determination of serum calcium and alkaline phosphatase levels, were normal. As she had undergone surgical treatment due to left mammary carcinoma two years previously, we first considered the possibility that the lesion was due to a metastatic tumor. But the progress of the tumor was very slow and we detected no sign of recurrence in her left breast nor any metastatic disease. Radiological analysis indicated an expansive radiolucent lesion without periosteal reaction, which was marked by fine bone lines (figure 1B). Whole bone survey showed no other potential lesions.
MRI revealed a monophasic bone tumor on both T1 and T2 weighted images, completely displacing the distal phalanx (figure 1C). Open biopsy was performed on January 28, 2005. A biopsy specimen revealed that the tumor was composed of numerous multinucleated osteoclast-type giant cells separated by intervening oval- to spindle-shaped stromal cells. No mitotic figures were evident (figures 1D, E).
Based on these results, we considered this tumor to be a type of giant cell-containing benign bone tumor; i.e., GCTB, giant cell reparative granuloma, aneurysmal bone cyst or brown tumors of hyperparathyroidism. An aneurysmal bone cyst and brown tumors of hyperparathyroidism were excluded, for the former should show fluid levels in the tumor by MRI [3], and the latter should be associated with abnormal serum levels of calcium, phosphorus, and alkaline phosphatase and should become multifocal. Although we could not find features of a giant cell reparative granuloma (i.e.; an irregular distribution of giant cells, a tendency to aggregate in clusters around the stromal hemorrhage, fibrotic stroma [6] and phagocytosed hemosiderin [2]), it was difficult to make a definitive differential diagnosis based on analysis of the fragmented biopsy specimen that would rule out a giant cell reparative granuloma. As both tumors tend to recur after curettage [4, 7] and the distal phalangeal bone was completely displaced by tumor cells, we recommended amputation at the PIP joint in order to make a diagnosis and to provide certain treatment. On February 14, 2005, her second toe was amputated.
Surgical pathology demonstrated a uniform distribution of giant cells, oval- to spindle-shaped stromal cells without fibrosis, and a lack of periosteal reaction despite the presence of tumor penetration, all of which were consistent with GCTB and led to a final diagnosis.
Acknowlegments: We are grateful to Ms. Flaminia Miyamasu for proofreading. n

References

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