Xueyan Yao, MD

Dermoscopy showed polylobular, whitish yellow, amorphous structures at the center of the lesion surrounded by a crown of vessels (Figure 1). Histopathology revealed hyperplastic crateriform lesions containing large eosinophilic intracytoplasmic inclusion bodies within keratinocytes (Figure 2). At follow-up 2 weeks after the biopsy, the patient presented with approximately 20 more reddish papules of varying sizes on the abdomen and back that presented as dome-shaped papules and had a typical umbilicated center. The clinical manifestations, dermoscopy, and pathology findings were consistent with molluscum contagiosum (MC).

Molluscum contagiosum was first described in 1814. It is a benign cutaneous infectious disease caused by a double-stranded DNA virus of the poxvirus family. Molluscum contagiosum lesions usually manifest clinically as dome-shaped, flesh-colored or translucent, umbilicated papules measuring 1 to 5 mm in diameter that are commonly distributed over the face, trunk, and extremities and usually are self-limiting.¹

Giant MC is rare and can be seen either in patients on immunosuppressive therapy or in those with diseases that can cause immunosuppression, such as human immunodeficiency virus, leukemia, atopic dermatitis, Wiskott-Aldrich syndrome, and sarcoidosis. In these instances, MC often is greater than 1 cm in diameter. Atypical variants may have an eczematous presentation or a lesion with secondary abscess formation and also can be spread widely over the body.² Due to these atypical appearances and large dimensions in immunocompromised patients, other dermatologic diseases should be considered in the differential diagnosis, such as basal cell carcinoma, keratoacanthoma, squamous cell carcinoma, cutaneous horn, cutaneous cryptococcosis, histoplasmosis, and xanthomatosis.³

In our patient, the differential diagnosis included keratoacanthoma, which may present as a solitary, discrete, round to oval, flesh-colored, umbilicated nodule with a central keratin-filled crater and has a rapid clinical evolution, usually regressing within 4 to 6 months.

Squamous cell carcinoma may appear as scaly red patches, open sores, warts, or elevated growths with a central depression and may crust or bleed. Basal cell carcinoma typically may appear as a dome-shaped skin nodule with visible blood vessels or sometimes presents as a red patch similar to eczema. Xanthomatosis often appears as yellow to orange, mostly asymptomatic, supple patches or plaques, usually with sharp and distinctive edges.

Ancillary diagnostic modalities such as dermoscopy may be used to improve diagnostic accuracy. The best known capillaroscopic feature of MC is the peripheral crown of vessels in a radial distribution. A study of 258 MC lesions highlighted that crown and crown plus radial arrangements are the most common vascular structure patterns under dermoscopy. In addition, polylobular amorphous white structures in the center of the lesions tend to be a feature of larger MC papules.⁴ Histologically, MC shows lobulated crateriform lesions, thickening of the epidermis into the dermis, and the typical appearance of large eosinophilic intracytoplasmic inclusion bodies within keratinocytes.⁵

There are several treatment options available for MC. Common modalities include liquid nitrogen cryospray, curettage, and electrocauterization. In immunocompromised patients, MC lesions usually are resistant to ordinary therapy. The efficacy of topical agents such as imiquimod, which can induce high levels of IFN-α and other cytokines, has been demonstrated in these patients.⁶ Cidofovir, a nucleoside analog that has potent antiviral properties, also can be included as a therapeutic option.³ Our patient’s largest MC lesion was treated with surgical excision, the 2 large lesions on the left side of the chest with cryotherapy, and the other small lesions with curettage.

Dermoscopy showed polylobular, whitish yellow, amorphous structures at the center of the lesion surrounded by a crown of vessels (Figure 1). Histopathology revealed hyperplastic crateriform lesions containing large eosinophilic intracytoplasmic inclusion bodies within keratinocytes (Figure 2). At follow-up 2 weeks after the biopsy, the patient presented with approximately 20 more reddish papules of varying sizes on the abdomen and back that presented as dome-shaped papules and had a typical umbilicated center. The clinical manifestations, dermoscopy, and pathology findings were consistent with molluscum contagiosum (MC).

Molluscum contagiosum was first described in 1814. It is a benign cutaneous infectious disease caused by a double-stranded DNA virus of the poxvirus family. Molluscum contagiosum lesions usually manifest clinically as dome-shaped, flesh-colored or translucent, umbilicated papules measuring 1 to 5 mm in diameter that are commonly distributed over the face, trunk, and extremities and usually are self-limiting.¹

Giant MC is rare and can be seen either in patients on immunosuppressive therapy or in those with diseases that can cause immunosuppression, such as human immunodeficiency virus, leukemia, atopic dermatitis, Wiskott-Aldrich syndrome, and sarcoidosis. In these instances, MC often is greater than 1 cm in diameter. Atypical variants may have an eczematous presentation or a lesion with secondary abscess formation and also can be spread widely over the body.² Due to these atypical appearances and large dimensions in immunocompromised patients, other dermatologic diseases should be considered in the differential diagnosis, such as basal cell carcinoma, keratoacanthoma, squamous cell carcinoma, cutaneous horn, cutaneous cryptococcosis, histoplasmosis, and xanthomatosis.³

In our patient, the differential diagnosis included keratoacanthoma, which may present as a solitary, discrete, round to oval, flesh-colored, umbilicated nodule with a central keratin-filled crater and has a rapid clinical evolution, usually regressing within 4 to 6 months.

Squamous cell carcinoma may appear as scaly red patches, open sores, warts, or elevated growths with a central depression and may crust or bleed. Basal cell carcinoma typically may appear as a dome-shaped skin nodule with visible blood vessels or sometimes presents as a red patch similar to eczema. Xanthomatosis often appears as yellow to orange, mostly asymptomatic, supple patches or plaques, usually with sharp and distinctive edges.

Ancillary diagnostic modalities such as dermoscopy may be used to improve diagnostic accuracy. The best known capillaroscopic feature of MC is the peripheral crown of vessels in a radial distribution. A study of 258 MC lesions highlighted that crown and crown plus radial arrangements are the most common vascular structure patterns under dermoscopy. In addition, polylobular amorphous white structures in the center of the lesions tend to be a feature of larger MC papules.⁴ Histologically, MC shows lobulated crateriform lesions, thickening of the epidermis into the dermis, and the typical appearance of large eosinophilic intracytoplasmic inclusion bodies within keratinocytes.⁵

There are several treatment options available for MC. Common modalities include liquid nitrogen cryospray, curettage, and electrocauterization. In immunocompromised patients, MC lesions usually are resistant to ordinary therapy. The efficacy of topical agents such as imiquimod, which can induce high levels of IFN-α and other cytokines, has been demonstrated in these patients.⁶ Cidofovir, a nucleoside analog that has potent antiviral properties, also can be included as a therapeutic option.³ Our patient’s largest MC lesion was treated with surgical excision, the 2 large lesions on the left side of the chest with cryotherapy, and the other small lesions with curettage.

Dermoscopy showed polylobular, whitish yellow, amorphous structures at the center of the lesion surrounded by a crown of vessels (Figure 1). Histopathology revealed hyperplastic crateriform lesions containing large eosinophilic intracytoplasmic inclusion bodies within keratinocytes (Figure 2). At follow-up 2 weeks after the biopsy, the patient presented with approximately 20 more reddish papules of varying sizes on the abdomen and back that presented as dome-shaped papules and had a typical umbilicated center. The clinical manifestations, dermoscopy, and pathology findings were consistent with molluscum contagiosum (MC).

Molluscum contagiosum was first described in 1814. It is a benign cutaneous infectious disease caused by a double-stranded DNA virus of the poxvirus family. Molluscum contagiosum lesions usually manifest clinically as dome-shaped, flesh-colored or translucent, umbilicated papules measuring 1 to 5 mm in diameter that are commonly distributed over the face, trunk, and extremities and usually are self-limiting.¹

Giant MC is rare and can be seen either in patients on immunosuppressive therapy or in those with diseases that can cause immunosuppression, such as human immunodeficiency virus, leukemia, atopic dermatitis, Wiskott-Aldrich syndrome, and sarcoidosis. In these instances, MC often is greater than 1 cm in diameter. Atypical variants may have an eczematous presentation or a lesion with secondary abscess formation and also can be spread widely over the body.² Due to these atypical appearances and large dimensions in immunocompromised patients, other dermatologic diseases should be considered in the differential diagnosis, such as basal cell carcinoma, keratoacanthoma, squamous cell carcinoma, cutaneous horn, cutaneous cryptococcosis, histoplasmosis, and xanthomatosis.³

In our patient, the differential diagnosis included keratoacanthoma, which may present as a solitary, discrete, round to oval, flesh-colored, umbilicated nodule with a central keratin-filled crater and has a rapid clinical evolution, usually regressing within 4 to 6 months.

Squamous cell carcinoma may appear as scaly red patches, open sores, warts, or elevated growths with a central depression and may crust or bleed. Basal cell carcinoma typically may appear as a dome-shaped skin nodule with visible blood vessels or sometimes presents as a red patch similar to eczema. Xanthomatosis often appears as yellow to orange, mostly asymptomatic, supple patches or plaques, usually with sharp and distinctive edges.

Ancillary diagnostic modalities such as dermoscopy may be used to improve diagnostic accuracy. The best known capillaroscopic feature of MC is the peripheral crown of vessels in a radial distribution. A study of 258 MC lesions highlighted that crown and crown plus radial arrangements are the most common vascular structure patterns under dermoscopy. In addition, polylobular amorphous white structures in the center of the lesions tend to be a feature of larger MC papules.⁴ Histologically, MC shows lobulated crateriform lesions, thickening of the epidermis into the dermis, and the typical appearance of large eosinophilic intracytoplasmic inclusion bodies within keratinocytes.⁵

There are several treatment options available for MC. Common modalities include liquid nitrogen cryospray, curettage, and electrocauterization. In immunocompromised patients, MC lesions usually are resistant to ordinary therapy. The efficacy of topical agents such as imiquimod, which can induce high levels of IFN-α and other cytokines, has been demonstrated in these patients.⁶ Cidofovir, a nucleoside analog that has potent antiviral properties, also can be included as a therapeutic option.³ Our patient’s largest MC lesion was treated with surgical excision, the 2 large lesions on the left side of the chest with cryotherapy, and the other small lesions with curettage.

The Diagnosis: Acute Contact Dermatitis

Dermoscopy demonstrated caterpillar hairs (Figure) and established the diagnosis of acute contact dermatitis due to a caterpillar. Upon further questioning, the patient recalled that something dustlike fell on the left cheek as she walked under some trees. The clinical and dermoscopic findings suggested a diagnosis of caterpillar dermatitis (family Limacodidae or Lymantriinae, order Lepidoptera). During the life cycle from young larvae to mature larvae, the quantities of the toxic thorns and hairs increase from 60,000 to 80,000 to 2,000,000 to 3,000,000. The toxic hairs measure 0.5 to 2.0 mm in length. They drop from the mature larvae's skin during desquamation as well as from the cocoon curing maturation to a moth. The hairs appear tubular and arrowlike with terminal spines.¹ The larvae are called "the fiery hot" in Chinese, which vividly describes the swelling and sensation of burning with immediate contact.

Eruption severity and distribution depend on exposure modality and intensity. Exposed body parts, including the face, neck, forearms, interdigital spaces, and dorsal aspects of the hands, most commonly are involved. The eruption can be immediate or delayed, occurring hours or even days after the first contact.2 Itching is intense and continuous, with intermittent worsening. Clinically, the eruption manifests with rose to bright red, round macules and papules. Although rare, skin manifestations can be accompanied by systemic symptoms, such as malaise, fever, and anaphylaxis syndrome.³ The cutaneous lesions may last for 3 to 4 days and subside, leaving a brownish macule.^1,4

The differential diagnosis includes acute herpes simplex, which presents as grouped vesicles on an erythematous base with itching or burning, and recurrences in the same location are common. Acute Sweet syndrome may appear as erythematous or edematous painful plaques with fever and neutrophilia. Acute urticaria appears as wheals with severe pruritus, and individual lesions can resolve within several hours. Insect bites often appear as itching or painful erythema or papules.

We sterilized the lesion with alcohol, removed the thorns as much as possible with ophthalmic forceps under the guidance of dermoscopy, and prescribed chloramphenicol ointment 1% twice daily. Our patient was completely cured within 24 hours with no systemic symptoms or pigmentation.

This case directly showed a novel usage of dermoscopy in diagnosis and therapy, especially in acute contact dermatitis. Small irritants such as caterpillar thorns and hairs easily can be observed and removed by dermoscopy devices with higher magnification.

The Diagnosis: Acute Contact Dermatitis

Dermoscopy demonstrated caterpillar hairs (Figure) and established the diagnosis of acute contact dermatitis due to a caterpillar. Upon further questioning, the patient recalled that something dustlike fell on the left cheek as she walked under some trees. The clinical and dermoscopic findings suggested a diagnosis of caterpillar dermatitis (family Limacodidae or Lymantriinae, order Lepidoptera). During the life cycle from young larvae to mature larvae, the quantities of the toxic thorns and hairs increase from 60,000 to 80,000 to 2,000,000 to 3,000,000. The toxic hairs measure 0.5 to 2.0 mm in length. They drop from the mature larvae's skin during desquamation as well as from the cocoon curing maturation to a moth. The hairs appear tubular and arrowlike with terminal spines.¹ The larvae are called "the fiery hot" in Chinese, which vividly describes the swelling and sensation of burning with immediate contact.

Eruption severity and distribution depend on exposure modality and intensity. Exposed body parts, including the face, neck, forearms, interdigital spaces, and dorsal aspects of the hands, most commonly are involved. The eruption can be immediate or delayed, occurring hours or even days after the first contact.2 Itching is intense and continuous, with intermittent worsening. Clinically, the eruption manifests with rose to bright red, round macules and papules. Although rare, skin manifestations can be accompanied by systemic symptoms, such as malaise, fever, and anaphylaxis syndrome.³ The cutaneous lesions may last for 3 to 4 days and subside, leaving a brownish macule.^1,4

The differential diagnosis includes acute herpes simplex, which presents as grouped vesicles on an erythematous base with itching or burning, and recurrences in the same location are common. Acute Sweet syndrome may appear as erythematous or edematous painful plaques with fever and neutrophilia. Acute urticaria appears as wheals with severe pruritus, and individual lesions can resolve within several hours. Insect bites often appear as itching or painful erythema or papules.

We sterilized the lesion with alcohol, removed the thorns as much as possible with ophthalmic forceps under the guidance of dermoscopy, and prescribed chloramphenicol ointment 1% twice daily. Our patient was completely cured within 24 hours with no systemic symptoms or pigmentation.

This case directly showed a novel usage of dermoscopy in diagnosis and therapy, especially in acute contact dermatitis. Small irritants such as caterpillar thorns and hairs easily can be observed and removed by dermoscopy devices with higher magnification.

The Diagnosis: Acute Contact Dermatitis

Dermoscopy demonstrated caterpillar hairs (Figure) and established the diagnosis of acute contact dermatitis due to a caterpillar. Upon further questioning, the patient recalled that something dustlike fell on the left cheek as she walked under some trees. The clinical and dermoscopic findings suggested a diagnosis of caterpillar dermatitis (family Limacodidae or Lymantriinae, order Lepidoptera). During the life cycle from young larvae to mature larvae, the quantities of the toxic thorns and hairs increase from 60,000 to 80,000 to 2,000,000 to 3,000,000. The toxic hairs measure 0.5 to 2.0 mm in length. They drop from the mature larvae's skin during desquamation as well as from the cocoon curing maturation to a moth. The hairs appear tubular and arrowlike with terminal spines.¹ The larvae are called "the fiery hot" in Chinese, which vividly describes the swelling and sensation of burning with immediate contact.

Eruption severity and distribution depend on exposure modality and intensity. Exposed body parts, including the face, neck, forearms, interdigital spaces, and dorsal aspects of the hands, most commonly are involved. The eruption can be immediate or delayed, occurring hours or even days after the first contact.2 Itching is intense and continuous, with intermittent worsening. Clinically, the eruption manifests with rose to bright red, round macules and papules. Although rare, skin manifestations can be accompanied by systemic symptoms, such as malaise, fever, and anaphylaxis syndrome.³ The cutaneous lesions may last for 3 to 4 days and subside, leaving a brownish macule.^1,4

The differential diagnosis includes acute herpes simplex, which presents as grouped vesicles on an erythematous base with itching or burning, and recurrences in the same location are common. Acute Sweet syndrome may appear as erythematous or edematous painful plaques with fever and neutrophilia. Acute urticaria appears as wheals with severe pruritus, and individual lesions can resolve within several hours. Insect bites often appear as itching or painful erythema or papules.

We sterilized the lesion with alcohol, removed the thorns as much as possible with ophthalmic forceps under the guidance of dermoscopy, and prescribed chloramphenicol ointment 1% twice daily. Our patient was completely cured within 24 hours with no systemic symptoms or pigmentation.

This case directly showed a novel usage of dermoscopy in diagnosis and therapy, especially in acute contact dermatitis. Small irritants such as caterpillar thorns and hairs easily can be observed and removed by dermoscopy devices with higher magnification.