Blue Naevus

HISTOPATHOLOGY-INDIA.NET

Path Quiz Case-81:

Diagnosis: Cellular Blue Naevus

Blue Naevus

Syn: Tieche's nevus ;Blue nevus of Jadassohn-Tieche

Blue naevus was first described by Tiesche in 1906 . These lesions may cause diagnostic difficulty in case of large size, involvement of subcutaneous tissue, asymmetrical pigmentation and presence of lymphnode metastasis.

Unlike benign melanocytic naevi, in blue naevi: 1) there is no evidence of diminution in cellularity and cell size towards the base of the lesion 2) no associated loss of pigmentation 3) no loss of proliferative activity.
The macroscopic bluish appearance is due to the presence of deep intradermal melanin pigment viewed through intact skin ( Tyndall effect)

Site: Although it usually occurs in skin, it has been reported in other locations, such as oral mucosa, sclera, uterine cervix, vagina, prostate, spermatic cord, pulmonary hilus, orbit, conjunctiva, maxillary sinus, breast, and lymph nodes.

Images: (DermAtlas):

COMMON BLUE NAEVUS:

This is a common subtype and presents as slate grey , blue or black papules usually less than 1cm in diameter. These are usually located on the head, hands and feet.

Histologically, these are ill-defined proliferation of elongated , sometimes finely branched dendritic, finely pigmented melanocytes within the dermis.Variable numbers of melanin laden macrophages (melanophages) containing large aggregates of melanin are present. A Grenz zone usually separates the lesion from the epidermis.
There may be increased cellularity and pigmentation close to the adnexae or along nerves and blood vessels.
Occasionally, the lesion is hypomelanotic (D/D dermatofibroma).
Usuall differential diagnosis include nevi of Ito, Ota and the Mongolian spot. Image link

CELLULAR BLUE NAEVUS:

Image Link1 ; Image Link2 ; Image Link3 ; Image Link4

Arthur Allan in 1949 for the first time recognised that this larger, cellular and often mitotically active melanocytic lesions were actually benign.
These acquired lesions are usually located in the sacrococcygeal/gluteal region and less common sites include face scalp and distal extremities.
These lesions clinically presents as nodule , tumour or plaques, usually 1 - 2 cm in diameter
(sometimes much larger).
Microscopically, this is a symmetrical lesion composed of two distinct cell types, dendritic melanocytes as in the common type, together with islands of plump , oval melanocytes with abundant cytoplasm. The plump cells have a round or oblong nucleus and central nucleolus. Often intranuclear cytoplasmic pseudoinclusions are present .
Often mitotic figures are noted (less than 2/sq mm). No atypical mitotic forms are present.
The deeper portions are often well circumscribed and can extend into the subcutis.
The growth pattern may be diffuse or nested . The terms used to describe the nested pattern include zellballen, fascicular and alveolar.
The differential diagnosis include malignant melanoma, fibrous histiocytoma, pigmented dermatofibrosarcoma protuberans and schwannoma.
IMAGE LINK:

CD34-positive cellular blue nevi.J Cutan Pathol. 2001 Mar;28(3):145-50.

OTHER VARIANTS OF BLUE NAEVUS

EPITHELIOID BLUE NAEVUS:
Microscopically, the lesion consists of two cell types i) globular to fusiform and heavily pigmented ii) polygonal or spindle shaped and light pigmented or non pigmented.
Epithelioid blue nevus of the oral mucosa: a rare histologic variant.Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2003 Oct;96(4):429-36.

ATYPICAL CELLULAR BLUE NAEVUS:
Proposed by Mihm et al, the lesion demonstrates clinico-pathological features intermediate between cellular blue naevus and malignant blue naevus. There is evidence of architectural and cytological atypia together with necrosis. No atypical mitoses were present and there was no evidence of metastasis.

"Atypical" blue nevus, "malignant" blue nevus, and "metastasizing" blue nevus: a critique in historical perspective of three concepts flawed fatally.Am J Dermatopathol. 2004 Oct;26(5):407-30.

MALIGNANT BLUE NAEVUS:

This lesion is noted in middle aged individuals, and is usually located on the scalp and rarely trunk and extremities. The patient usually complains of sudden increase in size of a longstanding lesion or there may be history of repeated unsuccessful local excision.

The lesion includes clear cut areas of malignant and benign blue naevus, or the histological appearances may resemble cellular blue naevus together with pleomorphism prominent atypical mitoses and areas of coagulative necrosis. Follow up of the cases reveal significant morbidity and death by metastatic disease.

Melanoma associated with blue nevus and melanoma mimicking cellular blue nevus: a clinicopathologic study of 10 cases on the spectrum of so-called 'malignant blue nevus'.Am J Surg Pathol. 2001 Mar;25(3):316-23.

Carney's Syndrome:

Syndrome is characterised by multiple pigmented lentigines of skin and mucous membrane (eg. epitheliod type blue naevi or usual type of blue naevi) , cardiac myxoma, endocrine overactivity syndromes and neurinomas including psammomatous melanotic schwannoma.
Epithelioid blue nevus and psammomatous melanotic schwannoma: the unusual pigmented skin tumors of the Carney complex.Semin Diagn Pathol. 1998 Aug;15(3):216-24.

Blue Naevus with Lymphnode metastasis:

Blue naevus with lymphnode metastasis is characterised by cellular blue naevus in the skin associated with the finding of melanocytes within a regional lymphnode .
In contrast to melanoma cells, blue naevus cells within lymphnodes are confined to capsule and do no show atypical features or mitosis. It has been suggested that the presence of cells of a blue naevus within a lymphnode is due to error during migration of melanocytes from the neural crest to the skin.

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Abstracts:

Plaque-type blue nevus of the oral cavity.Dermatology. 2005;211(3):224-33.

Malignant blue nevus with lymph node metastases in five-year-old girl.Croat Med J. 2005;46(3):463-6.

Congenital pauci-melanotic cellular blue nevus.J Cutan Pathol. 2004 ;31(4): 312-7.

Childhood malignant blue nevus of the ear associated with two intracranial melanocytic tumors-metastases or neurocutaneous melanosis?Hum Pathol. 2004 Oct;35(10):1292-6.

Eruptive multiple blue nevi of the penis: a clinical dermoscopic pathologic case study.J Cutan Pathol. 2004 Feb;31(2):185-8.

Amelanotic cellular blue nevus: a hypopigmented variant of the cellular blue nevus: clinicopathologic analysis of 20 cases.Am J Surg Pathol. 2002 ;26(11):1493-500.

"Compound blue nevus": a reappraisal of "superficial blue nevus with prominent intraepidermal dendritic melanocytes" with emphasis on dermoscopic and histopathologic features.J Am Acad Dermatol. 2002 Jan;46(1):85-9.

Epithelioid blue nevus: neoplasm Sui generis or variation on a theme?Am J Dermatopathol. 2000 Dec;22(6):473-88.

Large plaque-type blue nevus with subcutaneous cellular nodules.Am J Surg Pathol. 2000;24(1):92-9.

The relationship between melanocytes and peripheral nerve sheath cells (Part II): blue nevus with peripheral nerve sheath differentiation.Am J Dermatopathol. 2000 Jun;22(3):230-6.

Giant cellular blue nevus of the anterior chest wall mimicking metastatic melanoma to the breast: a case report.J Surg Oncol. 2000 Aug;74(4):278-81.

Pedunculated atypical cellular blue nevus.J Dermatol. 2000;27(11):730-3.

Amelanotic blue nevus: a variant of blue nevus.Am J Dermatopathol. 1999 ;21(3):225-8.

Cellular blue nevus with atypia (atypical cellular blue nevus): a clinicopathologic study of nine cases.J Cutan Pathol. 1998 May;25(5):252-8.

Blue nevus: classical types and new related entities. A differential diagnostic review.Pathol Res Pract. 1994;190(6):627-35.