This nevus is sometimes considered a variant of the Spitz nevus. It presents as a well-circumscribed deeply pigmented nodule on the thighs and extremities of young adults, usually women. Under the microscope, it resembles the Spitz nevus but is composed of spindled melanocytes with heavy melanin pigmentation. Kamino bodies are frequently present. As in a Spitz nevus, this nevus is symmetrical with maturation and lack of deep dermal mitotic figures.
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EPIDEMIOLOGY CHARACTERIZATION SYNONYMS
Pigmented spindle cell nevus. Clinical and histologic review of 90 cases.
Sagebiel RW, Chinn EK, Egbert BM.
Am J Surg Pathol 1984 Sep;8(9):645-53 Abstract quote
A clinical and histologic review of 90 patients with melanocytic lesions termed pigmented spindle cell nevi (PSCN) is reported.
The lesions are small in surface diameter, sharply confined both clinically and histologically, and often occur on the proximal extremities of young adults. They are generally of recent onset, moderately to heavily pigmented, and made up of nests of spindled cells confined to the epidermis and papillary dermis. There were 30 male and 60 female patients. Their average age was 25.3 years (ranging from 2.5 to 56 years). Lesions were located on the extremities in 61 cases (67%).
Follow-up was possible in 38 cases seen more than 6 months after histologic diagnosis and ranged up to 40 months (average 14 months). No local recurrence or distant spread was found. The importance of recognizing this lesion lies in differentiating it from malignant melanoma.
Conservative but complete excision has resulted in no recorded instances of local recurrence or distant spread.
CHARACTERIZATION RADIOLOGIC LABORATORY MARKERS DERMOSCOPY
Superficial black network: an additional dermoscopic clue for the diagnosis of pigmented spindle and/or epithelioid cell nevus.
Argenziano G, Soyer HP, Ferrara G, Piccolo D, Hofmann-Wellenhof R, Peris K, Staibano S, Chimenti S.
Department of Dermatology, Pathology Section, Federico II University of Naples, Italy.
Dermatology 2001;203(4):333-5 Abstract quote
Dermoscopy is a valuable method for improving the diagnostic accuracy of pigmented skin lesions. Specific dermoscopic criteria have been described for differentiating pigmented spindle and/or epithelioid cell nevi (SECN; Spitz nevi and Reed nevi) from cutaneous melanomas.
In the present study, we report an additional dermoscopic feature of SECN, namely a distinctive type of pigment network, described as superficial black network, which was observed in 10.5% of SECN.
Histopathologically, this network corresponds to focal areas of pigmented parakeratosis, producing a black reticulated appearance on the horizontal plane.
CHARACTERIZATION GENERAL VARIANTS CONJUNCTIVA
Pigmented spindle cell naevus of reed presenting in the conjunctiva.
Ophthalmic Pathology and Oncology Service, St Erik's Eye Hospital, Karolinska Institutet, Stockholm, Sweden.
Acta Ophthalmol Scand 2000 Feb;78(1):104-6 Abstract quote
PURPOSE: This study aimed to present the clinical and histopathological features of a pigmented spindle cell naevus (PSCN) appearing in the conjunctiva.
METHODS: Histopathological examination of the lesion following excision and review of the pertinent literature.
RESULTS: The features were consistent with those previously recognized in the skin as the PSCN of Reed.
CONCLUSION: The PSCN can appear in the conjunctiva and should not be confused with conjunctival melanoma.
HISTOLOGICAL TYPES CHARACTERIZATION GENERAL
Pigmented spindle cell naevus.
Requena L, Sanchez Yus E.
Department of Dermatology, University Hospital of San Carlos, Madrid, Spain.
Br J Dermatol 1990 Dec;123(6):757-63 Abstract quote
We report 22 cases of pigmented spindle cell naevus (PSCN). The usual appearance of these naevi is that of a heavily pigmented papule found mostly on the legs of young patients.
Histologically, PSCN was characterized by symmetrical proliferation of spindle-shaped pigmented melanocytes grouped in large junctional nests. Pagetoid spread of single cells in the overlying epidermis was frequently found.
In our opinion, PSCN is a distinctive benign acquired melanocytic naevus that in the past has been frequently misdiagnosed as atypical Spitz naevi or malignant melanoma.
The histologic spectrum of pigmented spindle cell nevus: a review of 120 cases with emphasis on atypical variants.
Barnhill RL, Barnhill MA, Berwick M, Mihm MC Jr.
Department of Pathology, Massachusetts General Hospital, Boston 02114.
Hum Pathol 1991 Jan;22(1):52-8 Abstract quote
The histopathologic features of 120 cases of pigmented spindled nevus (PSCN) from the years 1973 through 1988 were reviewed from a consultative practice heavily weighted with difficult nevomelanocytic lesions.
The patients' mean age was 25.2 years, and females outnumbered males (68 versus 52). Extremity lesions made up 69.6% of the total, with the thigh the most common site. The lesions were categorized into one of four variants of PSCN, based on the presence or absence of various architectural and cytologic parameters and involvement of the reticular dermis.
Thirteen cases (10.8%) were designated typical PSCN, and were characterized by fascicles of uniform pigmented spindle cells without cellular atypia and limited to the epidermis or papillary dermis.
Ninety-five cases (79.2%) were classified as atypical PSCN (PSCN with architectural and/or cytologic atypia). Some of the latter also demonstrated substantial numbers of epithelioid cells, thus exhibiting some overlap with Spitz nevus. Eight cases showed striking features of dysplastic nevus. Ten cases had fascicles of pigmented spindle cells involving the reticular dermis ("plexiform" PSCN). Two cases were designated as combined PSCN because of the presence of banal nevus cells in addition to the spindle cell component.
Clinical follow-up of a small group of patients has not suggested, to date, any aggressive behavior. Knowledge of PSCN and its atypical variants is important for discrimination from malignant melanoma.
VARIANTS KAMINO BODIES
Eosinophilic globules in pigmented spindle cell nevus.
Wistuba I, Gonzalez S.
Department of Pathology, Catholic University of Chile, School of Medicine, Santiago.
Am J Dermatopathol 1990 Jun;12(3):268-71 Abstract quote
Reed's pigmented spindle cell nevus is often misdiagnosed as malignant melanoma despite reliable clinical and histopathologic diagnostic features.
In the present report, 10 cases of pigmented spindle cell nevus were studied with step sections to identify Kamino's eosinophilic globules. Eighty percent of the cases disclosed numerous eosinophilic globules, supporting the hypothesis that this nevus is a variant of Spitz's nevus.
Kamino's eosinophilic globules could be considered another important sign for the differential diagnosis between pigmented spindle cell nevus and malignant melanoma.
CHARACTERIZATION SPECIAL STAINS IMMUNOPEROXIDASE PROLIFERATION MARKERS
Proliferative activities in Spitz nevus compared with melanocytic nevus and malignant melanoma using expression of PCNA/cyclin and mitotic rate.
Tu P, Miyauchi S, Miki Y.
Department of Dermatology, University of Ehime School of Medicine, Japan.
Am J Dermatopathol 1993 Aug;15(4):311-4 Abstract quote
Proliferative activity in Spitz nevus (SN) was determined using proliferating cell nuclear antigen (PCNA) immunostaining and by assessing the mitotic rate.
It was compared with that in compound melanocytic nevus (MN) and in malignant melanoma (MM). The PCNA index (number of positive cells/1,000 tumor cells) in SN was 72.8 +/- 45.5% (mean +/- SD), which was statistically significantly higher than that in MN (7.2 +/- 2.7%) and lower than that in MM (248.5 +/- 110%). The PCNA-positive cells in SN and MM were found both in dermal and junctional nests, while those in MN were found almost exclusively in the dermal nests. The mitotic rate in SN was 1.4 +/- 0.96%, while it was nothing in MN and 5.4 +/- 4.2% in MM.
There was a statistically significant correlation between the PCNA index and the mitotic rate at r = 0.8946, p < 0.001. The PCNA index, however, appeared to show the proliferative activity of SN more clearly than did the mitotic rate.
DIFFERENTIAL DIAGNOSIS KEY DIFFERENTIATING FEATURES DESMOPLASTIC NEVUS
Desmoplastic nevus: a distinct histologic variant of mixed spindle cell and epithelioid cell nevus.
Barr RJ, Morales RV, Graham JH.
Cancer 1980 Aug 1;46(3):557-64 Abstract quote
From a series of 75 cases of mixed spindle cell and epithelioid cell nevi, 14 were designated as desmoplastic nevi.
Junctional activity, theque formation, and pigmentation were uncommon features. As a result, desmoplastic nevi may be confused with a variety of fibrohistiocytic lesions. Well defined intranuclear invaginations of cytoplasm occurred in 12 cases, and were helpful in differentiating desmoplastic nevi from these lesions.
Desmoplastic malignant melanoma must also be considered in the microscopic differential diagnosis, but distinguishing features of desmoplastic melanoma include the presence of preexisting lentiginous melanoma, and necrosis of tumor cells and collagen.
Desmoplastic nevus was compared to the ordinary variants of mixed spindle cell and eipthelioid cell nevus in an attempt to define etiologic factors responsible for a desmoplastic reaction. No satisfactory explanation could be found since the clinical variables examined were not statistically different.
Melanoma resembling spindle and epithelioid cell nevus.
Arch Dermatol 1979 Dec;115(12):1416-20 Abstract quote
Three cases of malignant melanoma resembling spindle and epithelioid cell nevus histologically are presented. Lesions having histologic features of spindle and epithelioid cell nevus (Spitz nevus or juvenile melanoma) at or after puberty should be regarded with caution, particularly when they are heavily melanized. Such lesions are in a histologic "gray zone" and may be malignant.
PROGNOSIS AND TREATMENT CHARACTERIZATION PROGNOSTIC FACTORS GENERAL
Pigmented spindle cell nevus: a clinicopathologic analysis of ninety-five cases.
Sau P, Graham JH, Helwig EB.
Department of Dermatology and Pathology, Walter Reed Army Medical Center, Washington, DC 20307-5001.
J Am Acad Dermatol 1993 Apr;28(4):565-71 Abstract quote
BACKGROUND: Pigmented spindle cell nevus (PSCN) is often interpreted as a Spitz nevus or misdiagnosed as malignant melanoma.
OBJECTIVE: The purpose of this study was to analyze the clinical and histologic features and to determine the biologic behavior of 95 cases of PSCN.
METHODS: We reviewed clinical data, follow-up information, and microscopic features of all 95 cases of PSCN.
RESULTS: PSCNs are dark brown to black, 3 to 6 mm in diameter, and occur most commonly on the extremities (75%) and back (16%) with a predilection for the legs. These lesions are more common in women in the third decade of life. Microscopically, PSCNs are characterized by uniform, spindle-shaped, pigmented melanocytes. Although some histologic features overlap with those in spindle and epithelioid cell nevus, PSCN is a separate entity. In addition, PSCN must be differentiated from malignant melanoma. Fifty-seven patients (60%) observed for an average of 6 years did not develop local recurrence or metastasis.
CONCLUSION: PSCN is a distinctive, acquired, benign melanocytic lesion, that should not be confused with spindle and epithelioid cell nevus or malignant melanoma. Complete excision is recommended for treatment.
TREATMENT Complete excision
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DeMay RM. The Art and Science of Cytopathology. Volume 1 and 2. ASCP Press. 1996.
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Fitzpatrick's Dermatology in General Medicine. 5th Edition. McGraw-Hill. 1999.
Weiss SW and Goldblum JR. Enzinger and Weiss's Soft Tissue Tumors. Fourth Edition. Mosby 2001.
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