Cheek lesion.

A 55-year-old man consulted for a pigmented lesion on his left cheek

Dermoscopy revealed:

• an irregular broadened network
• rhomboidal structures

Pathology was in favor of a lentigo maligna melanoma in situ.

Nasal pigmented lesion

A 85-year-old woman consulted for a pigmented lesion on the tip of her nose.

Dermoscopy revealed:

• a pseudo-pigmented network (due to the facial localisation)
• asymmetric pigmentation of the follicular openings
• slate gray dots disposed as annular- granular structures

Clinical and dermoscopic features were in favor of a lentigo maligna melanoma which was confirmed by a punch biopsy.

Peppering

A 85-year-old woman consulted for a slowly enlarging pigmented lesion on her right cheek


Dermoscopy revealed a pseudonetwork which is characteristic of facial pigmented lesions.
Furthermore, dermoscopy showed multiple slate-grays dots or pepper-like granules realizing a typical an annular-granular pattern or peppering in favor of a lentigo maligna melanoma. A biopsy confirmed this diagnosis.

Peperring

Peppering or annular-granular pattern can also be present in lichen planus-like keratosis and actinic keratosis.
Some lentigo maligna melanomas exhibit this structure.

Lentigo maligna melanoma

A 70-year-old woman consulted for this light-brown pigmented lesion on her left cervical area.

Dermoscopy revealed slate-gray dots disposed in an annular-granular pattern in favor of a lentigo maligna melanoma which was confirmed by biopsies performed on the lesion.

This case of lentigo maligna melanoma (LMM) exhibited only a feature of annular-granular pattern.



Annular-granular structures can be seen in:

• lichen planus-like keratosis
• actinic keratosis
  

The other possible features of lentigo maligna melanoma are:

• asymmetric pigmented follicular openings
• dark rhomboïdal structures
• homogeneous areas

Other cases:1 2 3 4 5

Lentigo maligna simulating an actinic lentigo

A 72-year-old woman consulted for a pigmented lesion on her right forearm.


Dermoscopy revealed an asymmetric pigmented lesion with different shades of brown colour, fingerprint-like structures and moth-eaten borders. These dermoscopic signs are observed in actinic lentigos or flat seborrheic keratoses.
However, a biopsy revealed a lentigo maligna.
The lesion was excised and pathology confirmed the diagnosis of lentigo maligna melanoma in situ.


Facial lentigo maligna melanoma (LMM) typically features asymmetric follicular openings, annular-granular pattern, rhomboïdal structures and homogenous areas.

In our case of extra-facial LMM, the presentation was different and was masquerading as an actinic lentigo.

Extra-facial LMMs comprise 17,5% of LMMs. Extra-facial LMMs of men are predominantly localized on the trunk while the most frequent localization in women are on limbs. Extra-facial LMMs are thinner than facial LMMs at presentation and affect younger group of patients.

See the literature: Cox, Aitchison & Mackie. Extrafacial lentigo maligna melanoma: analysis of 71 cases and comparison with lentigo maligna melanoma of the head and neck. Brit Journal Dermatol 1998; 139: 439-43

Lentigo maligna melanoma

A 68-year-old man consulted for an enlarging dark pigmented lesion.


Dermoscopy revealed asymmetrical pigmented follicular openings, rhomboidal structures and some homogenous areas.
A biopsy confirmed the diagnosis of lentigo maligna . The lesion was completely excised and pathology revealed a lentigo maligna melanoma in situ.

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.

Lentigo maligna melanoma

A 58-year-old woman consulted for this non homogeneous lesion on her left forearm.



Dermoscopy revealed a lightly pigmented network that was focally darker on certain areas or absent of other areas, and the presence of rare brown dots.
The red area was due to a punch biopsy.


A biopsy was performed and revealed a lentigo maligna melanoma. The lesion was completely excised and pathology revealed LMM with a Breslow index at 0.10mm

Lentigo maligna melanoma

A 82-year-old woman presented a lentigo maligna melanoma .
Dermoscopy revealed an annular-granular pattern with slate-gray dots (rectangle), rhomboidal structures and a homogenous area (white circle).
A punch biopsy was performed on the darkest area and pathology revealed a lentigo maligna melanoma, Breslow thickness 1.6 mm.

Lentigo maligna melanoma

A 69-year-old woman consulted for a macular pigmented lesion of her right cheek. This multicoloured lesion was centered by a dark brown spot.




Dermoscopy focused on the darker area showed annular granular structures, asymetric follicular openings and rhomboidal structures very suggestive of lentigo maligna melanoma.


A biopsy was performed on the dark brown spot and revealed a lentigo maligna melanoma in situ.


The lesion was entirely removed and a graft was performed.
The pathology exam of the whole lesion revealed a breslow index at 0.46mm