Cellular Blue Nevi

 Ovoid, clear cells are abundant

image Clear cells show small, round to oval monomorphous nuclei; eosinophilic or clear cytoplasm

image Heavily pigmented spindled and dendritic cells alternate with clear cells

Top Differential Diagnoses

• Atypical cellular blue nevus

• Melanoma arising in or mimicking cellular blue nevus (malignant blue nevus)

• Desmoplastic melanoma

Diagnostic Checklist

• Clinical features
image Heavily pigmented black or blue nodule or plaque

• Pathologic features
image Should not show multiple mitoses or necrosis (both of which favor malignancy)

Clinical Image of a CBN
Gray to dark blue tumor on the scalp of a middle-aged woman shows central ulceration related to trauma. (Courtesy J. Finch, MD.)

Dermatoscopic Image of a CBN
Dermoscopy of the same lesion shows a uniformly gray nodule. (Courtesy J. Finch, MD.)

CBN at Scanning Magnification
At this low power, a conventional blue nevus (CBN) showing nodular growth with deep pushing border image is identified.

CBN at Low Magnification Showing Base of Lesion
The lesion is heavily pigmented image and shows small nests/nodules image, of oval to spindle-shaped melanocytes.



• Cellular blue nevus (CBN)


• Uncommon cellular variant of blue nevus

• Presents as large, blue to blue-black, well-circumscribed, multilobulated tumor composed of oval to spindle-shaped melanocytes



• Age
image Occurs in childhood and young adult life; mean: 33 years

• Sex
image Female predominance (F:M ~ 2:1)

• Ethnicity
image All affected


• Mostly occurs on sacrococcygeal regions and buttock but may also be located on scalp, neck, face, hands, and extremities (especially dorsal foot)


• Heavily pigmented, slow-growing, black or blue nodule or plaque typically ranging 1-2 cm and sometimes up to 6 cm in diameter

• Ulceration may be seen in lesions appearing in area with growth restriction, such as dorsal foot

• Rarely can be with satellitosis, characterized clinically by development of macules around a central papule or nodule, and may thus mimic melanoma


• Surgical approaches
image Simple excision


• Benign but may rarely recur
• Regional lymph node involvement and benign metastases to regional lymph nodes with CBN are rare, but well documented

image Resulting lymphadenopathy is prone to misdiagnosis as metastatic malignant melanoma

• Has rare potential for malignant transformation, and affected patients have poor clinical outcome


Histologic Features

• Architecture consists of central mass with adjacent ramifications
image These have dumbbell or peninsula-like shape occupying place of effaced hair follicles, deeply extending into subcutis

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Apr 24, 2017 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Cellular Blue Nevi

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