Quiz questions from dermoscopy of infectious dermatoses (Infectiouscopy/Entodermoscopy)

Which dermoscopic feature is typically seen in cutaneous myiasis?

1. Bird’s feet-like structures

2. Yellowish structure with black spines

3. Thorn crown-like structures

4. All the above

Dermoscopy of tungiasis shows:

1. Yellowish crusts with central black dots

2. Pearly white nodules with a central black punctum

3. Whitish homogeneous lesion with a central brown pigmented ring

4. Red papules with central ulceration

A male patient presented with generalized itching, which worsened at night. He also reported similar symptoms in family members. On examination, multiple erythematous papules were observed in the finger web spaces and the periumbilical area. Dermoscopy findings are shown in Figure 1. What is the name of this dermoscopic sign?

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Figure 1.

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1. Delta-wing jet with contrail

2. Setting sun sign

3. Little red riding hood sign

4. Jelly sign

In cutaneous leishmaniasis, the ‘white starburst-like pattern’ is observed during which stage?

1. Early lesions

2. Intermediate lesions

3. Late stages

4. Healing stages

‘Falooda seeds’ appearance on dermoscopy is seen in:

1. Palmoplantar warts

2. Filiform warts

3. Genital warts

4. Verruca plana

Figure 2 displays the ultraviolet dermoscopic image of a healthy individual’s face. Which organism is responsible for the characteristic fluorescence seen in this figure?

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Figure 2.

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What is the main dermoscopic feature of cutaneous larva migrans?

1. Brownish structureless areas in a segmental arrangement

2. Linear branching vessels

3. Central ulceration with scales

4. Yellowish nodules

Which pattern is commonly observed in the dermoscopy of molluscum contagiosum?

1. Blue-gray dots

2. Central yellowish-white polylobular amorphous structure

3. Brownish reticular pattern

4. Starburst pattern

A 25-year-old male patient presented with an unpleasant odor and yellowish discoloration of hair in both axillae. Dermoscopy was performed, and the findings are depicted in Figure 3. What dermoscopic signs are observed in this condition?

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Figure 3.

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Which of the following is a dermoscopic feature of lupus vulgaris?

1. Orange to golden background pigmentation

2. Linear telangiectasias

3. White structureless areas

4. All the above

Which of the following dermoscopic findings is indicative of white piedra?

1. Easily detachable white, bizarrely shaped, amorphous structures

2. Elongated tubular structures encircling the hair shaft and easily movable along it

3. Localized whitish areas along the hair shafts, resulting from fractured and frayed hair

4. White amorphous material locally encasing the hair

A 13-year-old girl presented with severe scalp itching for the past 3 months and has a history of similar complaints in her younger sister. Dermoscopy findings are shown in Figure 4. Which structures are seen?

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Figure 4.

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Whitish scales along plantar creases are seen on dermoscopy of:

1. Plantar warts

2. Plantar corn

3. Tinea pedis

4. Pitted keratolysis

In dermoscopy of Demodex folliculorum, what do whitish creamy threads suggest?

1. Tails

2. Body

3. Legs

4. Mouth parts

Which trichoscopic finding has the highest predictive value for diagnosing tinea capitis?

1. Black dots

2. Broken hairs

3. Comma hairs

4. Perifollicular scaling

Which trichoscopic feature is more commonly detected in Trichophyton tinea capitis compared to Microsporum tinea capitis?

1. Morse code-like hairs

2. Zigzag hairs

3. Bent hairs

4. Corkscrew hairs

What treatment should be recommended for a child with the dermoscopic findings depicted in Figure 5?

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Figure 5.

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1. Griseofulvin

2. Itraconazole

3. Fluconazole

4. Terbinafine

Dermoscopy of pitted keratolysis typically shows:

1. Irregular whitish structures

2. Heterogeneous architecture at the periphery of the craters

3. Scales along ridges

4. Yellowish areas

The dermoscopic features of Cydnidae pigmentation are:

1. Clusters of numerous oval to shiny brown globules and granules

2. Bizarre-shaped pigmented structures

3. Accentuated pigmentation along skin furrows and eccrine openings

4. All the above

A 56-year-old woman presented with asymptomatic discoloration of her left thumb nail for the past year. Despite treatment with oral antifungals, there was no improvement. Onychoscopy is shown in Figure 6. What is the diagnosis and the name of the dermoscopic sign depicted in Figure 6?

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Figure 6.

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Chick-pea flour pattern is seen on onychoscopy of:

1. White superficial onychomycosis

2. Endonyx

3. Distal lateral subungual onychomycosis

4. Proximal subungual onychomycosis

Which of the following onychoscopic signs has the highest sensitivity and specificity for the diagnosis of onychomycosis?

1. Ruin appearance

2. Longitudinal striae

3. Spikes on the proximal margin of onycholytic areas

4. Aurora borealis sign

Dendritic pattern on onychoscopy is seen in:

1. Distal lateral subungual onychomycosis

2. Proximal subungual onychomycosis

3. Superficial onychomycosis

4. Endonyx onychomycosis

Identify the onychoscopic sign shown in Figure 7 and specify the condition.

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Figure 7.

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Which of the following findings is specific to pityriasis versicolor as identified in dermoscopic studies?

1. White scales over a dull diffuse white or brown background

2. Folliculocentricity (perifollicular white halo)

3. Contrast halo sign (ring of alternate pigmentation surrounding the primary lesion)

4. All of the above

Which of the following dermoscopic features is commonly observed in leprosy across all its subtypes?

1. White structureless areas

2. Hyperpigmentation with irregular borders

3. Yellow/yellowish-orange areas

4. Peripheral hyperpigmentation

‘White jade coin pendant sign’ is a dermoscopic sign of:

1. Cutaneous histoplasmosis

2. Chromomycosis

3. Cutaneous talaromycosis

4. Basidiobolomycosis

A 12-year-old boy presented with multiple asymptomatic, skin-colored to hyperpigmented papules on his right hand. Dermoscopic examination is shown in Figure 8. What is the diagnosis?

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Figure 8.

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Which of the following diseases shows a ‘noodle pattern’ on dermoscopy?

1. Crusted scabies

2. Myiasis

3. Tungiasis

4. Phthiriasis

A 45-year-old female presented with acute onset painful grouped vesicular eruption of the right side of her abdomen extending to the back. Dermoscopy findings are shown in Figure 9. What is the name of this dermoscopic sign and what is the diagnosis?

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Figure 9.

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(d). Cutaneous myiasis is caused by the larval stage of different botflies. Dermoscopy of furuncular myiasis reveals bird feet-like structures corresponding to respiratory spiracles, yellowish structures with black barb-like spines extruding from the periphery, and a thorn-crown appearance due to black dots on the outer edge of the larva.^[1]

(c). A whitish homogeneous lesion with a central brown pigmented ring is characteristic of tungiasis, which is caused by the female sand flea (Tunga penetrans and Tunga trimamillata). The white areas correspond to the parasite’s dilated abdomen containing eggs, while the central light brown structure corresponds to the posterior segment of the parasite.^[2]

(a). Delta-wing jet with contrail (jet with trail) sign. It represents the burrow with the mite at the end, appearing as a dark triangle (mite; black arrow) followed by a thin, wavy line (burrow; blue arrow).^[3,4]

(c). Dermoscopic examination of early lesions of cutaneous leishmaniasis reveals yellow tear-shaped structures and vessels, whereas late lesions display a starburst pattern with peripheral vascular structures.^[4,5]

(a). Dermoscopy of palmoplantar warts reveals hemorrhagic and thrombosed black dots and globules, surrounded by a white halo, resembling wet basil seeds in falooda.

Answer: Cutibacterium acnes. Sebaceous gland openings exhibit fluorescence under ultraviolet light, which ranges in color from bright blue/green to yellow, orange, or red. This characteristic fluorescence can be particularly useful in diagnosing and monitoring acne vulgaris. Notably, orange fluorescence is due to the presence of porphyrins produced by C. acnes (formerly Propionibacterium acnes).^[8,9]

(a). Dermoscopy of cutaneous larva migrans reveals translucent, brownish, structureless areas arranged segmentally, corresponding to the body of the larva. In addition, dotted vessels representing empty burrows can also be observed.^[10]

(b). Dermoscopy of molluscum contagiosum typically reveals a central white-yellowish polylobular amorphous structure, surrounded by a crown of vessels.^[11,12]

Skewer sign and plume sign. Trichoscopy reveals golden-yellow, cotton-like deposits sticking to the affected hair shafts. A detailed view may show nodules and deposits with a flame-like appearance. Some hair shafts display waxy, yellowish nodules and deposits along their entire length, a feature referred to as the skewer sign. In addition, a localized pale-yellowish nodule can produce what is known as the plume sign.^[13,14]

(d). Dermoscopy of lupus vulgaris reveals a yellow background pigmentation with linear telangiectasias, which corresponds to the clinically observed apple jelly sign. This sign can also be seen in other granulomatous conditions. Lupus vulgaris additionally presents with white structureless areas, follicular plugs, yellow-white scales, dilated follicles, and erythema.^[4,15]

(d). White piedra presents as white amorphous material locally encasing the hair Dermoscopy of seborrheic dermatitis reveals easily detachable white, bizarrely shaped, amorphous structures. Elongated tubular structures that encircle the hair shaft and are easily movable along it, known as hair casts, can be seen in traction alopecia, folliculitis decalvans or idiopathically. Trichobacteriosis is identified by waxy and yellowish/whitish adherent aggregates forming a sheath around the axillary hair shaft. Trichorrhexis nodosa is characterized by localized whitish areas along the hair shafts, resulting from fractured and frayed hair.^[13,14,16]

In vivo dermoscopy can identify three stages of nits: active viable nits are ovoid, whitish-brown structures containing eggs or viable embryos, located close to the scalp; abortive nits are translucent with a condensed non-viable embryo and a dehiscing operculum, found about 5 mm or farther from the scalp; and empty nits are translucent whitish crystalline structures without an operculum, typically more than 1 cm away from the scalp.^[4,17]

(c). Dermoscopy of tinea pedis and manuum shows whitish scales along creases and brownish scales corresponding to dried vesicles.^[18]

(a). Dermoscopy of demodicosis reveals two distinct features: whitish, creamy, gelatinous threads known as Demodex tails, and dilated follicular openings containing gray or brown amorphous round plugs, which are surrounded by an erythematous halo, referred to as Demodex follicular openings.^[19]

(c). The most indicative trichoscopic findings of tinea capitis, known for their high predictive value, include comma hairs (51%), corkscrew hairs (32%), Morse code-like hairs (22%), zigzag hairs (21%), bent hairs (27%), block hairs (10%), and i-hairs (10%). In addition, other frequently observed but less characteristic trichoscopic features are broken hairs (57%), black dots (34%), perifollicular scaling (59%), and diffuse scaling (89%).^[20,21]

(d). Morse code-like hairs, zigzag hairs, bent hairs, and diffuse scaling are exclusively found in cases of Microsporum tinea capitis, occurring in 28%, 21%, 14%, and 14% of cases, respectively. In contrast, corkscrew hairs are more frequently observed in Trichophyton tinea capitis, with a prevalence of 55% compared to 10% in Microsporum tinea capitis.^[20,21]

(d). In Trichophyton tinea capitis, corkscrew hairs were more commonly detected compared to Microsporum tinea capitis (21/38, 55% vs 3/29, 10%).^[20] Given that corkscrew hairs are the main finding in the image, the likely causative organism is Trichophyton, so terbinafine should be used for treatment.^[22]

(b). Dermoscopy of pitted keratolysis shows pits and heterogenous architecture at the periphery of craters.^[23]

(d). Cydnidae pigmentation is caused by burrowing bugs. Their odorous secretions stain the skin. Dermoscopy shows brown globules and granules, bizzare-shaped pigmented structures, and accentuation of pigmentation along skin furrows and eccrine openings.^[24]

Green nail syndrome and green aurora sign. It is caused by Pseudomonas aeruginosa and the greenish discoloration occurs due to pyocyanin pigment. On onychoscopy, ‘green aurora’ sign is visualized.^[25]

(a). The ‘chick-pea flour pattern’ in white superficial onychomycosis refers to yellowish-white, opaque, and friable debris on the nail plate, predominantly near the proximal nail fold.^[26]

(d). The primary dermoscopic indicators of onychomycosis include the ‘ruin appearance,’ ‘longitudinal striae,’ and ‘spikes’ located at the proximal edge of onycholytic areas, with specificities of 99.38%, 83.78%, and 85.64%, respectively. The ‘aurora borealis’ sign demonstrated the greatest sensitivity and specificity.^[27]

(d). Dendritic pattern is seen in endonyx onychomycosis.^[28]

Aurora borealis sign, seen in distal lateral subungual onychomycosis. Aurora borealis represents areas of various colors ranging from whitish yellow to greenish-blue to bluish-gray to black in onycholytic areas.^[27]

(d). In both hypo- and hyperpigmented variants of pityriasis versicolor, white scales in skin furrows over a dull white or brown background are key dermoscopic characteristics. In addition, perifollicular white scaling, ‘contrast halo sign,’ a ring of alternating pigmentation around the main lesion, and folliculocentricity are also described.^[29,30]

(c). Yellow or yellowish-orange areas are among the most common dermoscopic findings observed in all subtypes of leprosy, making it a reliable marker for the disease in dermoscopic examinations.^[30,31]

(c). The ‘white jade coin pendant sign’ in Talaromyces marneffei infection is characterized by a circular or nearly circular whitish amorphous structure with a central keratin plug or hemorrhage.^[32,33]

Verruca vulgaris. The dermoscopic characteristics of common warts include brown dots, dotted vessels, and black dots or globules (indicative of thrombosed vessels) against a white background.^[4,30]

(a). Noodle pattern is seen on dermoscopy of crusted scabies due to congregation of multiple burrows at one site.^[34]

‘Halo sign’ of herpes zoster. The ‘halo sign’ results from the contrast between the yellowish-brown crusted center of the vesicular lesions and the red hue of the erythematous background, forming an annular pattern around each vesicle.^[35-37]