Dermal Spindle Cell Research Articles

Cutaneous Atypical Fibroxanthoma With Osteoclast-Like Giant Cell: A Rare but Diagnostic Pitfall.

Atypical fibroxanthoma (AFX) is a dermal-based, low-grade neoplasm with no specific lineage of differentiation. The occurrence of AFX with osteoclast-like giant cells is exceptionally rare. Less than 20 cases have been reported in the literature. A 77-year-old man with a medical history of multiple basal and squamous cell carcinomas of the skin, presented with a progressively growing erythematous nodule on the sun-damaged right central parietal scalp. A shave biopsy showed a dermal spindle cell proliferation accompanied by numerous osteoclast-like multinucleated giant cells and predominant atypical mitotic figures. The immunohistochemical staining showed a diffuse positive staining for CD68 and SMA, patchy staining for CD10, and negative staining for SOX-10, pan-cytokeratin, CK5/6, S100, CD34, and desmin. The tumor was completely excised with negative margins. A subsequent follow-up over a period of 13 months showed no recurrence. Distinguishing AFX with osteoclast-like giant cells from both malignant and benign skin lesions with osteoclast-like giant cells is crucial. Although AFX tumors display worrisome malignant histologic features, most cases have a favorable prognosis with a local recurrence rate below 5% and exceedingly rare metastasis.

DP11 Dermal plexiform spindle cell lipoma: a perplexing entity

Abstract We present a 66-year-old man who presented to dermatology with an unusual lesion. An outdoor worker with prior history of melanoma, the patient was referred with a new pigmented lesion adjacent to his melanoma scar. This was identified as a seborrhoeic keratosis and the patient was reassured. Following a full body examination, an incidental lesion was identified on the left anterior shoulder. The lesion measured 9 × 7 mm, was dermal-based, dome-shaped, soft to palpation and skin coloured with light peripheral pigmentation. The lesion was featureless upon dermoscopic examination. The clinical differential diagnosis included neurofibroma and an intradermal naevus. The lesion was narrowly excised. Histological examination revealed an ill-defined, wedge-shaped dermal lesion with tumour fascicles with a vaguely plexiform arrangement. The widely separated fascicles comprised loosely arranged spindle cells, mature adipocytes and scant collagen fibres with a myxoid stroma. The spindle cells were stained diffusely with CD34 immunohistochemistry. The adipocytes and a proportion of spindle cells (around 20–30%) were stained with S100. The features were in keeping with a dermal plexiform spindle cell lipoma. Spindle cell lipoma is an uncommon benign, histologically distinct tumour, accounting for 1.5% of all adipocytic neoplasms. More common within the subcutis, it is rare for these lesions to present with a purely intradermal location. Dermal spindle cell lipomas tend to be less cellular than their subcutaneous counterpart. This coupled with the variable representation of the three constituent lesion components (spindle cells, mature adipocytes and fibromucinous stroma) results in a wide range of possible differential diagnoses. The plexiform variant of spindle cell lipoma (PSCL) is a poorly recognized form with even greater potential for misdiagnosis, particularly with plexiform neurofibroma—­leading to an erroneous diagnosis of neurofibromatosis. Dermal PSCL is an exceptionally rare diagnosis with only eight cases reported in the literature thus far. Here, we report a further case of dermal plexiform spindle cell lipoma, with, for the first-time, corresponding clinical images. In our summary, we discuss in detail the potential diagnostic pitfalls of this rare tumour and how to best employ immunohistochemical staining to avoid them.

Cutaneous nerve sheath tumours, non‐infectious polycystic kidney disease, renal granulomas, nephrocalcinosis and crystals: Incidental pathological findings in pond‐living goldfish (Carassius auratus, Linnaeus)

AbstractIn an adult male goldfish (Carassius auratus, Linnaeus), an unusual combination of diseases was detected. The owner noted a bilateral, asymmetrical distention of the abdomen, multiple cutaneous masses and an altered swimming behaviour over the course of time; diagnostic work‐up was not requested and euthanasia elected. Grossly, the cutaneous masses were whitish, discrete, extremely friable. Histologically, the dermis was multifocally expanded by moderately cellular, unencapsulated neoplastic tissue, composed of dermal spindle cells. The celomic cavity opening revealed a gelatinous multicystic mass, corresponding to the kidney, which replicated several cysts compressing the residual parenchyma. Histologically, sparse, late‐stage granulomas, basophilic intratubular deposits and crystals were also detected. No mycobacterial DNA was detected in tissue with granulomas. No parasites were detected in the histological sections examined. Diagnoses of cutaneous nerve sheath tumours, polycystic kidney disease, renal late‐stage granulomas, nephrocalcinosis and crystals were formulated. The authors had proposed to recapitulate each single condition.

Skeletal deformities in a case of digitocutaneous dysplasia

We present a case of a 2 year old female with digital fibrous lesions, dysmorphic facial features, stridor, sensorineural hearing loss, and scoliosis. The patient surgical history included digital amputations at the interphalangeal joint line bilaterally on the middle, ring, and little finger. Physical exam demonstrated knee and elbow flexion contractures and a left ankle varus contracture. Radiographic evaluation revealed several aggressive fibromas in the proximal femori and tibia (Figure 1) and a mild dextroconvex lumbar scoliosis (Figure 2) [1,2]. Biopsy of a digital lesions revealed a dermal spindle cell proliferation without atypia or necrosis, and perinuclear inclusions on H&E and trichrome stains. Comparative genomic hybridization and single nucleotide polymorphism genotyping revealed two adjacent duplications of the DMD gene (OMIM 400477): a duplication of 83 kb from the cytogenic band Xp21.2 to Xp 21.1 and a duplication of 555 kb within the cytogenetic band of Xp21.2.

25671 Nonepidemic variant of Kaposi sarcoma in an immunocompetent HIV-negative male

A 30-year-old man with no significant past medical history presented for evaluation of a growth on his nose that appeared 3 months prior. He reported having several female sexual partners in the past with whom he did not consistently use condoms. HIV testing 6 months prior was negative. Physical examination revealed a solitary 7-mm pink to red papule on the nasal dorsum. No other skin or mucosal lesions were identified. There was no cervical, axillary, or inguinal lymphadenopathy. Laboratory workup including CBC, CMP, serum immunoglobulins, and SPEP were unremarkable. HIV 1 and 2, and HTLV-1 and 2 were negative. Shave biopsy revealed a dermal spindle cell proliferation arranged in short intersecting fascicles admixed with plasma cells and occasional mitotic figures. Immunohistochemical studies showed spindled cells stained with CD34. CD31 and HHV8 staining were also positive. Kaposi sarcoma (KS) is a rare angioproliferative disorder associated with infection with human herpes virus 8 (HHV-8). There are 4 recognized epidemiologic forms: classic, endemic, epidemic, and iatrogenic. A recently described fifth type, nonepidemic KS, occurs in a rare subset of individuals who do not fit other classifications. This includes HIV-negative individuals without detectable cellular or humoral immunodeficiency. This subset has been described as clinically similar to classic KS with limited disease, but occurring in younger men. Although nonepidemic KS is generally indolent with a good prognosis, secondary lymphoproliferative disorders, including Castleman disease and lymphoma, have been reported. This report highlights a case of nonepidemic KS and discusses important relevant diagnostic and management considerations.

Cutaneous Eccrine Adenolipoma with a Spindle Cell Component

Abstract Introduction/Objective Cutaneous adenolipoma is a rare, benign variant of solitary lipoma characterized by a mature adipocytic proliferation with entrapped eccrine or apocrine sweat glands. It is found predominately in middle-aged females, with a predilection for lower extremities including the thigh and gluteal regions. Cutaneous adenolipoma is presumed to be a hamartomatous process. Herein, we report a unique case of a cutaneous eccrine adenolipoma with a spindle cell component, namely, an early evolving spindle cell adenolipoma. Methods A 43-year-old female with a recurrent history of hidradenitis presented with a 2.7 cm x 1.5 cm x 0.7 cm soft, mobile nodule on the right posterior thigh. It had been present for at least four months and clinically resembled a lipoma. An excisional punch biopsy was performed for pathological evaluation. A concurrent nevus lipomatosus superficialis was diagnosed from the right perineum. Results Gross examination of the thigh nodule revealed fragments of a tan-yellow, lobulated, fatty lesion. Microscopic examination demonstrated a benign lipomatous proliferation with entrapped eccrine glands associated with a surrounding spindle cell stroma. Initial differential diagnosis included a cutaneous eccrine adenolipoma variant and a cutaneous mixed solitary hamartoma composed of admixed neural, eccrine and lipomatous components. Immunohistochemical staining showed uptake for CD34 and CD10 in the spindle cell stromal component, but negative for desmin and S100. Based on our histopathological findings, our diagnosis of an eccrine cutaneous adenolipoma with a spindle cell component was rendered. This unique lesion displayed features of an evolving spindle cell lipoma with entrapped sweat glands, which may be viewed as an early stage of a dermal spindle cell adenolipoma. Conclusion Cutaneous eccrine adenolipoma is a rare, benign lipomatous neoplasm with entrapped sweat glands that can also show a spindle cell component. We share this rare lesion exemplifying the histomorphological spectrum of a lipomatous hamartoma and to highlight the recognition of a cutaneous adenolipoma.

Soft Tissue Special Issue: Cutaneous Pleomorphic Spindle Cell Tumors.

This manuscript provides an overview of pleomorphic spindle cell tumors presenting on sun-damaged skin of the elderly and includes discussions of atypical fibroxanthoma, pleomorphic dermal sarcoma, spindle cell and metaplastic squamous cell carcinoma, spindle cell and dedifferentiated melanoma and poorly differentiated cutaneous angiosarcoma. These tumors share many of the clinical presenting and histological features, making confident diagnosis challenging. A reliable and robust diagnosis is necessary to predict behavior as the biologic potential of these tumors ranges from benign (e.g. atypical fibroxanthoma) to outright malignant with poor survival rates (e.g. cutaneous angiosarcoma). The salient clinical, histologic and immunohistochemical characteristics are discussed in detail with emphasis on distinguishing features and differential diagnosis to provide the reader with a better understanding of these entities and helpful clues for a more robust diagnosis.

Expression of TLE1 in Malignant Melanoma With Spindle Cell Morphology: A Potential Diagnostic Pitfall

Transducer-like enhancer of split 1 (TLE1) immunohistochemistry is widely used as a biomarker of synovial sarcoma. Spindle cell or desmoplastic melanoma can morphologically mimic synovial sarcoma. The aim of this study was to investigate the expression of TLE1 in melanomas with a spindle cell morphology. A search of the surgical pathology files resulted in 57 cases of melanomas diagnosed with a spindle cell or desmoplastic component. After review, 8 cases had no definitive dermal spindle cell component and 7 cases had insufficient tissue remaining and were excluded from the study. A total of 42 melanomas were examined for TLE1 immunohistochemistry using a mouse monoclonal antibody (Cell Marque, clone 1F5). Strength and percentage of nuclear TLE1 positivity was graded on a scale from 0 to 3+. Staining for TLE1 was considered positive for 2 to 3+ and negative for 0 to 1+. Nuclear TLE1 expression was identified in 24 (57%) of the 42 melanoma cases with spindle cell morphology (2+, n = 14; 3+, n = 10). TLE1 was considered negative in 18 cases (43%), of which most contained weak staining (1+, n = 14 [33%]) and only a small subset did not show any staining (0, n = 4 [10%]). TLE1 frequently highlights melanomas with spindle cell morphology and is a potential diagnostic pitfall. Therefore, when evaluating spindle cell tumors in which the differential may include both a melanoma and synovial sarcoma, TLE1 expression should be interpreted with caution and in conjunction with an immunohistochemical panel.

Dermatofibrosarcoma Protuberans: An Unusual Parotid Swelling - A Case Report

Background: Dermatofibrosarcoma protuberans (DFSP) is a slowly growing tumor. It has a high recurrence rate. The tumor is characterized by dermal spindle cell proliferation with infiltration of subcutaneous tissue, and expression of CD34 on immunnohistochemistry is pathgnomic. Main observation: We observed a 46-years-old female patient complaining of recurrent fixed swelling in the parotid region that was diagnosed as DSFP. The tumor had been surgically excised and the patient was referred for adjuvant radiotherapy and a follow-up every month for 2 years with no reported recurrence. Conclusion: Although rare, DFSP requires a high index of suspicion if there is recurrent painless, cutaneous, and multinodular lesion in the parotid region. In this context, wide local excision (>3 cm margins) combined with post-operative radiotherapy plays a fundamental role in the management of DFSP patients.

Plaque-like Myofibroblastic Tumor: 2 Cases of This Unusual Dermal Tumor Which Occurs in Infancy and Early Childhood

Plaque-like myofibroblastic tumor (PLMT) is a rare dermal spindle cell tumor which occurs in infancy or childhood within the first 4 years of life. The tumor is often pruritic and mostly presents on the lower back. We describe 2 cases with characteristic clinical and histological features of this entity, thus adding to the 10 cases which have so far been reported. Histologically, the lesion resembles a dermatofibroma. However, diffuse and uniform immunohistochemical staining with smooth muscle actin favors a myofibroblastic lineage. PLMT should be considered in the differential diagnosis of a dermal spindle cell tumor in the pediatric age-group.

S-100 protein expressing spindle cells in spindle cell lipoma: a diagnostic pitfall.

Spindle cell lipoma represents a distinct clinicopathological entity and is related to cellular angiofibroma and mammary-type myofibroblastoma. Spindle cell lipomas are composed of mature lipogenic cells and a variable number of CD34-positive spindle cells that show loss of retinoblastoma protein expression. Spindle cell lipomas occasionally express S-100 protein. We studied one case of purely dermal spindle cell lipoma and four cases of classical subcutaneous spindle cell lipoma arising in one female and four male patients (age ranged from 55 to 69years). The neoplasms arose on the nose, the chin, the neck, the forehead and retroauricular, and all lesions had been marginally or incompletely excised. The studied cases showed classical histological and immunohistochemical features of spindle cell lipoma and, in addition, strong expression of S-100 protein by spindle-shaped tumour cells. S-100-expression in spindle cell lipoma may cause problems in the differential diagnosis with neural and melanocytic neoplasms and emphasizes the plasticity of the spindle cells in spindle cell lipoma.

The Adventitial Angioproliferation in Human Immunodeficiency Virus Associated Large Artery Vasculopathy is Not a Manifestation of Kaposi Sarcoma

Introduction: Human immunodeficiency virus-associated large artery vasculopathy (HIV-vasculopathy) is characterized by distinctive transmural microanatomical alterations, including adventitial angioproliferation, similar to that described in early cutaneous Kaposi sarcoma (KS). Human herpesvirus-8 (HHV8), the etiological agent of KS, is identifiable in tissue sections. The aim of this study was to investigate, based on HHV8-latent nuclear antigen-1 (HHV8-LNA-1) immunohistochemical and HHV8 polymerase chain reaction (PCR) testing, whether KS is the cause of the angioproliferation. Materials and Methods: Sections from 20 large arteries, ten each with HIV-associated occlusive and aneurysmal vasculopathy and ten biopsies with early cutaneous KS from 30 anti-retroviral therapy naive patients were appraised microscopically and subjected to HHV8-LNA-1 immunostaining. Arterial sections were also subjected to HHV8 PCR investigation with appropriate positive and negative controls. Results: The microscopic large arterial adventitial alterations included a dissecting proliferation of capillary-caliber vasculature, surrounded by mixed inflammation, microhemorrhages, hemosiderin and vasa vasorum intimomedial fibrosis, and hypertrophy. Ten vessels also demonstrated adventitial leukocytoclastic and lymphocytic vasculitis. Immunohistochemical and PCR detection of HHV8 was consistently negative. Skin biopsies of KS shared the vascular adventitial alterations, but vasculitis and thrombosis were absent. Endothelial and dermal spindle cells were immunopositive for HHV8. Conclusion: The adventitial angioproliferation in large arteries with HIV-vasculopathy is not a manifestation of KS. The exact roles of HIV, including interaction with co-infective agents and cellular and subcellular responses in the induction of vasculopathic and vasa vasorum abnormalities, including adventitial angioinflammatory alterations, require accelerated investigation for improved disease understanding and patient management.

A Case of Myxoid Dermatofibrosarcoma Protuberans

Dermatofibrosarcoma protuberans (DFSP) is a slow-growing dermal spindle cell tumor. Its rare myxoid variant is characterized by extensive myxoid degeneration. We report a case of myxoid DFSP of the lower abdomen in a 35-year-old man. Histopathologically, the tumor consisted of spindle-shaped cells that were strongly positive for CD34 with a typical storiform pattern and myxoid stromal changes.

Dermatofibrosarcoma protuberans in a 10-year-old child

Dermatofibrosarcoma protuberans is a rare mesenchymal malignancy in childhood and adolescence. The tumor is characterized by dermal spindle cell proliferation with infiltration of subcutaneous tissue, expression of CD34, and a specific fusion of the platelet-derived growth factor beta with the collagen type 1alpha1 gene. We observed a 10-year-old girl with a medaillon-like, asymptomatic plaque on the chest that was diagnosed as DSFP. The tumor was completely removed by delayed Mohs surgery. Follow-up so far has shown a complete response. The prognosis of dermatofibrosarcoma protuberans in children is excellent as long as early diagnosis is followed by complete excision with Mohs surgery as a golden standard.

Desmoplastic melanoma associated with an intraepidermal lentiginous lesion: case report and literature review

Desmoplastic melanoma tends to present as firm, amelanotic papules. Microscopically, it reveals a proliferation of fusiform cells in the dermis and variable collagen deposition, as well as intraepidermal melanocytic proliferation of lentiginous type in most cases. Biopsy in a 61-year-old white male patient, who had received a diagnosis of lentigo maligna on his face 10 years before, revealed a proliferation of dermal pigmented spindle cells and collagen deposition, reaching the deep reticular dermis, with a lentiginous component. Immunohistochemistry with S-100, Melan-A and WT1 showed positivity, but it was weak with HMB45. Desmoplastic melanoma associated with lentigo maligna was diagnosed. Several authors discuss whether desmoplastic melanoma represents a progression from the lentiginous component or arises "de novo". Desmoplastic melanoma represents a minority of cases of primary cutaneous melanoma (less than 4%). Identification of lentigo maligna indicates that desmoplastic melanoma should be carefully investigated.

Microvenular Hemangioma Presenting With Numerous Bilateral Macules, Patches, and Plaques

Microvenular hemangioma (MVH) is a rare, slowly growing, benign vascular tumor that typically presents as a solitary enlarging plaque or nodule on the trunk or the extremities of young to middle-aged adults. A minority of MVH present with multiple lesions that are either gradually or suddenly acquired (eruptive MVH). Herein, we report a case of a 53-year-old woman who progressively developed numerous bilateral MVHs presenting as enlarging, blanching, erythematous to violaceous macules, patches, and plaques over the proximal thighs and axillae. Two biopsies exhibited the irregular branching venules with inconspicuous lumina lacking endothelial atypia and associated with dermal fibrosis characteristic of MVH. Immunophenotypically, the endothelium expressed Wilms Tumor 1, CD31, CD34, and erythrocyte-type glucose transporter protein (GLUT-1) GLUT-1 focally and was negative for Human herpes virus 8 and the lymphatic marker D2-40. In addition, numerous dermal spindle cells expressing CD34 and procollagen, putative fibrocytes, surrounded the thickened dermal collagen bundles and small vessels of MVH implicating a reactive/reparative (proliferative) process due to an unrecognized cutaneous injury. A review of MVH summarizing its clinicopathologic findings and its natural history is presented.

Myxoid Dermatofibrosarcoma Protuberans of the vulva with myoid nodules: Clinicopathologic and Immunohistochemical study of a case

Dermatofibrosarcoma protuberans is a slow growing dermal spindle cell tumor seldom seen in the vulva and its myxoid variant, a rare type of dermatofibrosarcoma protuberans is characterised by extensive myxoid degeneration. We present the case of a 62 year old woman with an enlarging vulval swelling. Mass was excised surgically. Histopathologically the tumor consisted of uniform spindle-shaped cells showing strong positivity with CD34. In addition to the typical storiform pattern and lace like infiltration, prominent myxoid stromal changes were seen. Herein we report an interesting case of myxoid dermatofibrosarcoma protuberans, uncommonly reported in the dermatopathology literature.

Two Cases of Male Nipple Leiomyoma

We describe 2 cases of male nipple leiomyoma. A 70-year-old man had a painful subcutaneous tumor on his left nipple of 6 months duration. Histopathology disclosed dermal spindle cells with oval-shaped nuclei forming interlacing bundles with irregular pattern. Glandular elements were absent. The spindle cells were positive to α-smooth muscle actin, desmin, and vimentin. Estrogen receptor (ER) and progesterone receptor (PrR) were negative. We diagnosed this case as male leiomyoma of the nipple. Another patient was a 61-year-old man with gynecomastia induced by spironolactone of 6 months duration. He also had a painful nodule on his left nipple and histopathology disclosed spindle-shaped tumor cells as in the previous patient. The tumor was accompanied by glandular elements in the deep dermis and subcutaneous tissue, which showed apocrine secretion and were positive for α-smooth muscle actin, ER, and PrR. These glandular elements were interpreted as mammary gland. But ER and PrR stain did not show positive results for leiomyoma in the upper dermis. To the best of our knowledge, this is the first report of male idiopathic and gynecomastia-induced leiomyoma with ER and PrR staining.

Transbronchial fine needle aspiration (TBFNA) diagnosis of metastatic pleomorphic sarcoma arising from a dermal sarcoma (MFH) of the scalp

An 82-year-old man underwent investigations for a right perihilar mass in November 2011. He had a previous history of malignant fibrous histiocytoma (pleomorphic sarcoma) of the scalp which was excised in October 2009. TBFNA cytology showed single, multinucleated, large pleo-morphic malignant cells that were positive for Vimentin and CD10. Review of the histology showed a dermal spindle cell tumour displaying morphology reminiscent of an atypical fibrox-anthoma but which was invading the subcutis and abutting the deep fascia. The tumour was CD10+ and negative for cytokeratins, melanocytic and other markers including SMA, CD99 and Desmin. The morphology and immunoprofile was that of a malignant fibrous histiocytoma, as previously reported. There was no lym-phovascular space invasion or perineural invasion. Although peripheral margins were well clear, the clearance from the deep margin was only 0.3 mm. Pleomorphic sarcomas account for a large proportion of sarcomas in late adulthood, with a local recurrence rate of 19–31%, a metastatic rate of 31–35% (lungs 90%) and a 5-year survival of 65–70%. This case highlights the cytological criteria for the diagnosis of pleomorphic sarcoma and also confirms that deeply invasive AFX-like dermal tumours are best classified as pleomorphic sarcomas to better indicate their metastatic potential.

A Subungual Blue Naevus Showing Expansile Growth

A 64-year-old woman presented with a 3-year history of brownish, longitudinal melanonychia on the left third fingernail with no associated symptoms. Physical examination revealed that approximately 25% of the nail plate was covered with scattered, brownish, longitudinal, pigmented streaks. There were no visible nail plate changes, and periungual pigmentation was not evident. Lymphadenopathy was not present. After nail avulsion, a 0.2 × 0.3 cm irregular pigmented macule and peripheral scattered tiny macules were observed (Fig. 1a). Routine laboratory investigations and physical examination were unremarkable. The punch biopsy demonstrated a poorly circumscribed, dermal spindle cell proliferation separated from the overlying epidermis by a Grenz zone. There were bipolar melanocytes with elongated dendritic processes, some containing cytoplasmic melanin, along with scattered melanophages (Fig. 2a). Mitotic figures were not present and there was no pleomorphism. The dendritic cells were positive for S-100, HMB 45, and MART-1. These findings were consistent with a common blue naevus, and regular follow-up of the lesion was recommended. The size of the melanonychia increased over time, until approximately 80% of the nail plate was involved at a 3-year follow-up. The lesion remained asymptomatic. After repeated nail avulsion, a 1 × 0.7 cm homogenous dark black macule was observed in the nail bed (Fig. 1b), which did not involve the periungual skin or proximal nail fold. We conducted a second biopsy under local anaesthesia. The specimen demonstrated an increased cellular infiltration of dermal dendritic cells (Fig. 2b), which extended into the mid-dermis, but did not involve the subcutaneous adipose tissue. There were no mitotic figures or atypical cells. These findings were also consistent with a common blue naevus. We recommended excising the lesion because of its enlargement, but the patient declined. Ten months later, the lesion involved the entire nail bed (Fig. 1c), although it had not spread to the periungual skin or proximal nail fold. A third punch biopsy was performed and demonstrated pigmented dendritic cells with scattered epithelioid cells with vesicular nuclei (Fig. 2c). These dendritic cells were vertically oriented and penetrated into the deep mid-dermis. Pigmented, round, epithelioid cells with variable melanophages were present. This sample demonstrated some biphasic pattern of dermal cells, but did not have the typical dumbbell pattern of a cellular blue naevus. There was no significant cytological atypia, and there were no mitotic figures. The lesional cells were positive for S-100, HMB 45 and MART-1, but negative for Ki-67. As the vertically-oriented dendritic cells were increasing in depth penetration over time, removal of the entire lesion was strongly recommended. The lesion was subsequently excised completely and the patient received a nail bed graft.