Giant Molluscum Contagiosum Presenting as Foot Tumors in an Immunocompetent Female

To the Editor: Molluscum contagiosum is a common viral disease produced by the poxvirus (molluscum contagiosum virus). Clinically the cutaneous lesions are multiple, umbilicated papules, which usually appear on the face, trunk, and extremities in children.1 Giant type may be frequently seen in patients with atopic dermatitis or immunosuppressors.2 Although the molluscum lesion may appear on any skin surface of the body, a lesion on the sole is extremely rare especially the giant type.3–11 This article reports a very rare case of giant molluscum contagiosum presenting as a couple of foot tumors with smooth surface in an immunocompetent female. CASE REPORT A 53-year-old woman presented with red tumors increasing gradually on the left foot for half a year. About half a year ago, the patient found a small pale red and tender tumor on the inner side of her left foot, and the tumor gradually increased to the size of peanuts. The surface was smooth. She felt no pain, pruritus, or other conscious symptoms. A few days ago, a new similar lesion appeared on the sole of the same foot. So she sought medical help at our department. She was healthy in the past and had no history of infectious diseases or genetic disease in the family. Physical examination revealed a pale red and tender tumor measuring approximately 1.0 × 1.2 cm with irregular shape on the inner side and a similar smaller lesion on the sole of the left foot, with a clear boundary and smooth surface. There was no umbilical concave, ulceration, crust, or haphalgesia (Figs. 1A, B). She had no other similar lesions else.FIGURE 1.: A, A pale red and tender tumor with irregular shape on the inner side of the left foot. B, Other smaller pale red and tender tumor on the sole of the left foot.Blood routine test, urine routine test, stool routine test, blood coagulation routine test, preoperative 4 items (hepatitis B, hepatitis C, syphilis, HIV), thyroid function, and tumor marker test were normal. Skin biopsy of the bigger lesion revealed hyperacanthosis and molluscum bodies within the acanthosis (Fig. 2).FIGURE 2.: A, Skin biopsy of the bigger lesion revealed hyperacanthosis and several molluscum bodies within the acanthosis (×100). B, A typical magnified molluscum body.Based on the clinical manifestations, and histopathologic findings of skin biopsy, the patient was diagnosed with giant molluscum contagiosum. The lesions of this patient were partly removed by skin biopsy, the rest were treated with cryotherapy. There was no evidence of recurrence during 1 year of follow-up. DISCUSSION Molluscum contagiosum is a contagious infection caused by an molluscum contagiosum virus, the sole member of the Molluscipox genus of Poxviridae.12 In children, the disease is usually transmitted by close physical contact or autoinoculation, whereas in adults, it is mainly through sexual transmission.5 It is characterized by multiple umbilicated papules, which usually appear on the face, trunk, and extremities and more common in children.1 The diagnosis is generally easy because of its characteristic cutaneous feature of umbilicated papules.13 However, atypical clinical presentations and atypical localizations may occur, especially in the setting of immunosuppression.5 The giant variant is a rare clinical manifestation that appears as a cutaneous tumor. It usually occurs in immunocompromised patients but can also occur in immunocompetent children. Besides, molluscum contagiosum of the sole is rare, and only few cases have been previously reported. In our case, the patient was an immunocompetent female, and the lesions presented as isolated tumor on the inner side and the sole of the foot. The atypical presentation made diagnosis more challenging. The initial differential diagnosis of the tumor included skin tag, anal fistula, molluscum contagiosum, verruca vulgaris, fibroma, and various skin tumors.13 Owing to the histopathologic examination, our patient was finally made the diagnosis of giant molluscum contagiosum and treated timely and effectively. Except histopathologic examination, a Tzanck smear also is useful in showing typical molluscum bodies.5 However, the most painlessness method is dermoscopy that can reveal multiple shiny, white clods within the lesion.13 Alternative treatments for giant molluscum contagiosum include cryotherapy with liquid nitrogen, surgical excision followed by cauterization of the base with electrodessication, or chemical agents such as silver nitrate, phenol, and trichloroacetic acid.2 CONCLUSION There was extremely rare case with giant molluscum contagiosum in immunocompetent adults on the foot have been reported in literature. When dealing with a tumor or nodule of the foot, we should consider giant molluscum contagiosum as a differential diagnosis. Besides histopathologic examination and a Tzanck smear, dermoscopy is also a useful noninvasive tool.