Unusual localization of a dermatofibroma

A 53-year-old man consulted for this firm tumor on his 5th left finger. Clinical diagnoses were an acquired fibrokeratoma or a wart.


Dermoscopy revealed a peripheral homogeneous pigmentation and a
central white scarlike patch in favor of a dermatofibroma.

The lesion was excised and pathology confirmed this diagnosis of dermatofibroma.

Dermatofibromas are usually localized on the extremities , shoulders, thighs, buttocks.
Digital localization is rarely reported in the literature*.
Dermoscopy allows a more accurate diagnosis before excision of digital tumors.

* T. Yamamoto et al. Dermatofibroma of the digit: report of six cases.Dermatology 2003; 207:79-81

Other cases of dermatofibromas
1 2 3 4 5 6 7 8 9 10 11 12

Patchy network in a congenital melanocytic nevus

A 11-year-old girl presented a congenital melanocytic nevus on her left thigh.

Dermoscopy revealed a globular pattern and the presence of a patchy network (white circle)



A regular follow-up did not show any changing.

Recurrent lentigo maligna melanoma

A 74-year-old woman consulted for this pigmented lesion on her left cheek. She had been operated on 6 years before for a lentigo maligna melanoma. The excision was complete.

A pigmentation recurred slowly 4 years after the excision.

Dermoscopy revealed a dark brown annular-granular pattern.

A biopsy confirmed the diagnosis of recurrence of the lentigo maligna melanoma and the patient was operated on for a second time.

The other possible dermoscopic signs of a lentigo maligna melanoma are:

• asymmetric follicular openings
• rhomboïdal structures
  
• homogenous areas
• milky red areas
  

The 3 main differential diagnoses of lentigo maligna melanoma are:

• actinic lentigo and flat seborrheic keratosis: pseudo-network, milia-like cysts, finger-print like structures, moth-eaten border or jelly-like edge (jelly sign)
  

• pigmented actinic keratosis: usually presence of surface scale, broken-up pseudonetwork
  

• pigmented basal cell carcinoma: blue-gray ovoïd nests, blue gray globules, leaf-like areas, spoke-wheel structures, ulcerations, arborizing vessels

It is important to know that dermoscopy of pigmented actinic keratoses can reveal the same dermoscopic structures as lentigo maligna melanoma namely rhomboïdal structures and annular-granular pattern.
In this cases dermoscopy is not sufficient to allow an accurate discrimination between a pigmented AK and a LMM, but dermoscopy helps to find the correct area for biopsy, for example the darker area.

Dermatofibroma

A 65-year-old man consulted for firm pigmented lesion on his right leg.


Dermoscopy featured:

• a central white scarlike patch
• a peripheral pigment network
• ring-like structures

in favor of a dermatofibroma.



Other cases of dermatofibromas
1 2 3 4 5 6 7 8 9 10 11 12

Basal cell carcinoma

A 70-year-old woman consulted for a black ulcerated lesion on her left groin.


Dermoscopy displayed:
- absence of pigment network
- ulceration (white arrow)
- large blue gray ovoid nest (double arrow)
- delicate leaf-like areas (white circle)
in favor of a basal cell carcinoma

Globule-like structures and ring-like structures

A 45-year-old man consulted for a pigmented firm tumor on his right shoulder.
Firm aspect on palpation and dermoscopic feature were in favor of a dermatofibroma.


Brown globule-like structures and ring-like structures (red circle) were observed.

Globulelike structures are formed because the rete ridges are often flat, confluent, and hyperpigmented .
Ringlike structures are a kind of globule with a darker peripheral rim.

Fissures and ridges were also displayed in this case (arrows)

The most frequent dermoscopic patterns observed in dermatofibromas are the central white
scar- like patch and the peripheral delicate pigment network.
Globule-like structures, ring-like structures, fissures and ridges are less usual structures in this kind of tumor.


Recent litterature about dermoscopy of dermatofibromas:
Pedro Zaballos, Susana Puig, Alex Llambrich, Josep Malvehy. Dermoscopy of Dermatofibromas. A Prospective Morphological Study of 412 Cases. Arch Dermatol. 2008;144(1):75-83

Other cases of dermatofibromas
1 2 3 4 5 6 7 8 9 10 11 12

Glomerular vessels

A 72-year-old woman consulted for this pink lesion on her right leg.
Dermoscopy revealed spared glomerular vessels in favor of a Bowen disease.

Wart

Dermoscopy may be sometimes useful to confirm the diagnosis of wart, when it is clinically atypical. In this case, the verruca vulgaris, located on the foot, was pink.
Dermoscopy showed dotted vessels surrounded by a whitish halo