Medallion-like dermal dendrocyte hamartoma

Abstract:  Medallion-like dermal dendrocyte hamartomas are rare congenital cutaneous lesions, with only three occurrences reported in the English language literature. They present at birth as asymptomatic circular, oval, or triangular well-circumscribed, atrophic patches. Typically, they have an erythematous or yellow-brown hue and a characteristic pliable, wrinkled surface; subtle telangiectases may also be appreciated. They may be misdiagnosed as atrophoderma, cutis aplasia, or anetoderma. All reported patients have been female. Characteristic histologic findings include epidermal atrophy and the presence of a CD34-positive spindle cell proliferation in the dermis. This spindle cell proliferation represents a population of dermal dendrocytes, which are bone marrow-derived cells that are believed to function as antigen-presenting cells that contribute to the function of the skin immune system. Little is known about the pathophysiology of medallion-like dermal dendrocyte hamartomas. We present a patient with this entity and review similar presentations reported in the literature.     

徽章样真皮树突细胞错构瘤三例

【摘要】 报道3例徽章样真皮树突细胞错构瘤。2例男性,1例女性,年龄2 ～ 38岁。3例患者均表现为先天发生的徽章样轻度萎缩斑,随身体按比例长大,边界清楚,表面有明显扩张的静脉,无自觉症状。3例患者均有相似的组织病理改变,表现为表皮萎缩,真皮有梭形细胞增生。这些增生的梭形细胞CD34、?育a因子和波形蛋白阳性,而S100、CD68、CD1a、CD31和平滑肌肌动蛋白均阴性。3例患者均未予特殊治疗,随访观察3 ～ 4年,皮损仅随身体略有长大。     

Medallion-like dermal dendrocyte hamartoma: a case misdiagnosed as neurofibroma

Medallion-like dermal dendrocyte hamartoma is a rare congenital lesion, comprised of a benign dermal proliferation of fusiform cells that stain positive for CD34, often positive for factor XIIIa, and negative for S100. It has a highly characteristic clinical presentation consisting of a well-circumscribed atrophic and wrinkled patch located on the upper trunk or neck that remains stable with time. We report a case of an 11-year-old boy with a typical medallion-like dermal dendrocyte hamartoma on the nape of the neck that was previously misdiagnosed as neurofibroma on the basis of initial histological examination that was later reevaluated due to lack of clinical correlation. Three previously-reported cases of medallion-like dermal dendrocyte hamartoma also have had a previous histological misdiagnosis of probable neurofibroma; other reported cases have been misdiagnosed as congenital atrophic dermatofibrosarcoma protuberans. Clinical correlation and immunostaining are particularly important for the recognition of this rare benign lesion.     

Medallion-like dermal dendrocyte hamartoma: the main diagnostic pitfall is congenital atrophic dermatofibrosarcoma

Medallion-like dermal dendrocyte hamartoma is a newly described and rare clinical and pathological entity. This congenital, round, erythematous and atrophic lesion in the thoracic area is histologically characterized by a CD34+ dermal and hypodermal spindle-cell infiltration. We describe the clinical, histopathological, cytological and molecular features of three cases of dermal dendrocyte hamartoma. In all the cases, atrophic congenital dermatofibrosarcoma protuberans (DFSP) was the first histological diagnosis. In one case, wide surgery had been performed on the basis of the clinical and histological presentation. The histological pattern was similar in all the cases: epidermal atrophy and a spindle to ovoid cell proliferation in the dermis and in the subcutaneous fat. Immunochemical staining for CD34 and factor XIIIa was positive. Cytogenetic and molecular studies were performed; no chromosomal abnormality nor translocation t(17;22)(q22;q13) was observed. Fluorescence in situ hybridization analysis did not reveal the DFSP fusion gene COL1A1-PDGFB . We observed that the main diagnostic pitfall of medallion-like dermal dendrocyte hamartoma is atrophic congenital DFSP due to clinical and histological similarities. We emphasize that molecular studies to eliminate the t(17;22)(q22;q13) translocation of DFSP may provide determinant elements for diagnosis in order to avoid unnecessary mutilating surgery.     

Medallion‐like dermal dendrocyte hamartoma: A rare congenital CD34‐positive dermal lesion clinically and pathologically overlapping with fibroblastic connective tissue nevus

Both medallion‐like dermal dendrocyte hamartoma and fibroblastic connective tissue nevus are rare benign dermal lesions composed of CD34‐positive spindle cells. Although regarded as different diseases, it is sometimes difficult to distinguish between them due to their clinical and pathological similarities. We present a case of medallion‐like dermal dendrocyte hamartoma that could also be diagnosed as fibroblastic connective tissue nevus and propose the possibility of overlap in these diseases.     

Hypocellular medallion-like dermal dendrocyte hamartoma (plaque-like CD34-positive dermal fibroma)

Medallion-like dermal dendrocyte hamartoma (MLDDH) is a recently described congenital dermal neoplasm. Only 11 cases have been reported in the English literature and therefore its clinical and pathological manifestations are not completely defined. We report the case of a 20-year-old male presenting with a round, erythematous, atrophic plaque on the midline of the anterior aspect of the neck. The lesion was asymptomatic and was stable since birth. A skin biopsy was performed. Histological examination showed a band like hypocellular fibrotic area in the superficial reticular dermis, which did not spread to subcutaneous tissue. The cells were CD34-positive and S100 and CD56-negative. Elastic fibers were present. Altogether the morphological and immunostaining features were neither suggestive of dermatofibrosarcoma protuberans nor neurofibroma. Thus, the pathological findings were consistent with MLDDH. Clinical differential diagnosis includes anetoderma, aplasia cutis, or atrophic DFSP. Histological differential was made with atrophic scar and striae distensae. Although the histological findings were not identical to those described recently as characteristic, the clinical features were suggestive enough to make the diagnosis of MLDDH. Therefore in our experience, the MLDDH spectrum might include lesions with variable cellular density, which can show similar clinical manifestations.     

Hypocellular medallion‐like dermal dendrocyte hamartoma on the abdomen of a 25 year old male

Medallion‐like dermal dendrocyte hamartoma is a rare congenital lesion that is more commonly seen in females. It often presents at birth on the neck or upper trunk as a well‐circumscribed, atrophic patch with wrinkling of the overlying skin. Clinically, the differential diagnosis includes atrophoderma, anetoderma, and congenital atrophic dermatofibrosarcoma protuberans. Histologic findings show epidermal atrophy and dermal spindle cell proliferation that is CD34 positive, along with Factor XIIIa in the original reports. Due to this CD34 positivity, another name for the lesion is plaque‐like CD34+ dermal fibroma. We present a unique patient case as he is male and the lesion is located on his abdomen. Further reports and studies need to be done for thorough understanding of this neoplasm.     

Lymphocyte trafficking in psoriasis: a new perspective emphasizing the dermal dendrocyte with active dermal recruitment mediated via endothelial cells followed by intra-epidermal T-cell activation

Prominent within the inflammatory infiltrate of psoriasis are HLA-DR positive T lymphocytes and factor XIIIa positive dermal dendrocytes. Many investigators studying psoriasis have assumed that the HLA-DR positive T cells are activated, and thereby capable of producing lymphokines such as gamma interferon. However, by immunohistochemical analysis, greater than 95% of the dermal T cells in psoriatic lesions are Ki-67 negative, which suggests that they are in a resting or non-cycling (Go) state. In contrast to the dermal T-cell population, the epidermal T-cell population contains a greater population of Ki-67 positive lymphocytes. The entry of the T cells into the epidermis is, therefore, apparently associated with an important activation event, which in all likelihood involves interaction with the keratinocyte. The presence of activated intraepidermal T cells has been substantiated by the ability to detect gamma interferon mRNA by polymerase chain reaction in epidermal sheets of psoriatic lesions. The pathophysiologic implication in psoriasis for these distinctions and compartmentalization involving dermal and epidermal T cells are placed into the context of a cascade of cellular trafficking events, which are further dissected into a specific network of molecular mediators of inflammation. This report suggests that more attention should be placed on the microenvironment of the skin, with specific emphasis on the mechanism by which T cells accumulate in the dermis and epidermis, and elucidation of the selective inductive and recruitment capabilities of endothelial cells, perivascular dermal dendrocytes, and keratinocytes.     

Nodular post-kala-azar dermal leishmaniasis: a distinct histopathological entity

Post-kala-azar dermal leishmaniasis (PKDL) is an infrequently occurring sequel to treated visceral leishmaniasis. Diagnosis, particularly in non-endemic areas, is difficult because the clinical appearances may be subtle and simulate lepromatous leprosy. The histopathology of the condition has been a neglected subject. Nodular lesions constitute one of the large variety of lesions that can be seen in PKDL. This paper describes the histopathology of such lesions in 26 patients seen over a period of approximately 8 years in a non-endemic setting. All the biopsies had strikingly similar light microscopic features with characteristic findings: a dense lymphohistiocytic infiltrate beneath an atrophic epidermis, pronounced follicular plugging, vascular hyalinization and collagen changes and negative Fite stain. Tbese allow a definite diagnosis of PKDL even in the absence of demonstrable Leishman-Donovan (L-D) bodies.     

Primary dermal melanoma: a distinct subtype of melanoma

BACKGROUND: The term primary dermal melanoma has been used to describe a subtype of melanoma confined to the dermis and/or subcutaneous fat that histologically simulates metastasis but is associated with an unexpectedly prolonged survival. We report 7 cases of primary dermal melanoma diagnosed from 1998 to 2002 with no identifiable junctional or epidermal component or nevoid precursor. Histopathologic and immunohistochemical features were compared with known cases of cutaneous metastasis and nodular melanoma in an attempt to differentiate this entity from clinical and pathologic mimics. OBSERVATIONS: Seven patients had a single dermal and/or subcutaneous focus of melanoma. Metastatic staging workup findings were negative, including results from sentinel node and imaging studies. Mean Breslow depth was 7.0 mm, and mean maximum tumor diameter was 6.2 mm. The study cohort showed 100% survival at mean follow-up of 41 months (range, 10-64 months). Immunohistochemical analysis with S100, HMB-45, Ki-67, CD34, and p75 antibodies showed no significant staining patterns compared with metastatic and nodular melanomas. CONCLUSIONS: Primary dermal melanoma appears to be a distinct subtype of melanoma based on the excellent prognosis associated with this case series and others. Additional research focusing on cause, appropriate staging, and outcome of previously identified solitary dermal metastasis is warranted to further delineate this entity.     

Clinicopathological study of crateriform verruca: Crateriform epithelial lesions histopathologically distinct from keratoacanthoma

Keratoacanthoma (KA) is a distinct clinicopathological entity, but it is often confused with other crateriform tumors. This study re‐examined the clinicopathological features of 380 crateriform epithelial tumors with a central keratin plug. Seventy‐six tumors (20%) had histopathological features that differed from solitary KA and were more verruca‐like, and we designated these lesions as crateriform verruca (CFV). We performed clinicopathological re‐examination of these neoplasms with a crateriform architecture and epithelial lip‐like structures similar to KA, which also displayed histopathological features reminiscent of verruca vulgaris, such as finger‐like exophytic projections with hyperkeratosis and acanthosis, focal hypergranulosis and arborization. Clinical data on CFV were also summarized. The main histopathological differences from KA were that CFV showed proliferation of keratinocytes with a similar size and regular arrangement, and the base of CFV was well demarcated without endophytic growth. Interestingly, some CFV were partly composed of epithelial cells with large pink cytoplasm in the upper malpighian layer between papillomatous projections. Furthermore, areas of trichilemmal‐like keratinization without formation of the granular layer were seen in some lesions. These types of CFV were hardly distinguishable from KA, unless it is recognized that CFV may contain trichilemmal keratinization‐like areas accompanied by large epithelial cells with eosinophilic cytoplasm. We have proposed the term CFV for these verrucous neoplasms to differentiate them from KA.     

Eccrine angiomatous hamartoma: a rare skin lesion with diverse histological features

Eccrine angiomatous hamartoma (EAH) is an exceedingly rare benign tumor-like lesion prevalent in childhood which may produce pain and marked sweating. The histological features include proliferation of eccrine sweat glands and angiomatous capillary channels. We report an 8-year-old girl who had a single lesion on her left lower leg. Physical examination revealed a slightly elevated, 4×7 cm erythematous plaque on the lateral aspect of left leg. Sweating in the lesion was evoked by physical work or emotional stress. There was no pain or tenderness associated with the lesion. The patient had no history of trauma to the site. These lesions were clinically angiomatous, and we obtained the diagnosis by histopathological examination. Histopathological examination of the lesion showed increased numbers of eccrine glands, as well as dilated vascular channels in the deep dermis and subcutaneous tissue. These findings are consistent with EAH.     

Cutaneous silica granuloma: a lesion that might be clinically underdiagnosed

Cutaneous silica granuloma is a poorly understood, uncommon condition. There have been relatively few reports of cutaneous silica granuloma despite the well-known ubiquitous nature of silica in the environment. The characteristic latency period between the time of silica exposure to the time of clinical onset of granuloma, lack of clear-cut histories of exposure in most cases and likelihood of spontaneous resolution, may challenge the diagnosis. Thus, cutaneous silica granuloma might be a lesion that is often underdiagnosed. Here we describe a patient with characteristic findings of cutaneous silica granuloma.     

Rhabdomyomatous mesenchymal hamartoma: an unusual dermal entity with a report of two cases and a review of the literature

BACKGROUND: Rhabdomyomatous mesenchymal hamartoma (RMH) is a rare congenital lesion of the dermis and soft tissues consisting of a disordered and varied collection of mature adipose tissue, skeletal muscle, adnexal elements and nerve bundles. This entity exists under various names including striated muscle hamartoma, congenital midline hamartoma, and hamartoma of cutaneous adnexa and mesenchyme. Several published cases report the occurrence of RMH within the setting of other uncommon congenital abnormalities. METHODS: We report the clinical and pathologic features of two cases of rhabdomyomatous mesenchymal hamartoma. Patient 1 is a 71-year-old man who presented for removal of a nodule located on his temple that had been traumatized during a recent haircut. Patient 2 is a 4-month-old infant with amnion rupture sequence and rare craniofacial abnormalities including facial clefts, microphthalmia, bilateral colobomas, and a mobile fingerlike projection above the left medial canthus. RESULTS: Histological examination in both cases showed a deep dermal and subcutaneous fat collection of disorganized skeletal muscle fibers, adipose and neural tissue, and adnexal structures. Characteristically, the skeletal muscle approximated folliculosebaceous structures in a haphazard manner. CONCLUSIONS: RMH is a rare benign condition of the deep dermis and subcutaneous fat with only 22 cases existing in the English literature. To our knowledge, this is the first report of an elderly man presenting with RMH, presumptively present since birth. There was no evidence of cellular or malignant degeneration. While the etiology of RMH is unknown, possible explanations include aberrancy in the embryonic migration of mesodermally derived tissues or a genetic defect predisposing to the formation of hamartomas.     

A case of cutaneous extranodal natural killer/T-cell lymphoma clinically and histopathologically mimicking interface dermatitis

Extranodal natural killer/T-cell lymphoma (ENKTL) is a rare but aggressive cancer characterised by angiocentric and angiodestructive infiltration by NK-cells, or cytotoxic T-cell types. Histopathologically, ENKTL shows a multinodular or diffuse infiltration localised to vascular structures, resulting in angiodestruction and necrosis. We present a patient with an initially suspected diagnosis of benign interface dermatitis with a differential diagnosis of mycosis fungoides that was later found to be an aggressive extranodal natural killer/T-cell lymphoma of a nasal type and with a dismal prognosis.     

Folliculocystic and collagenous hamartoma of tuberous sclerosis complex,not always a single cutaneous lesion

Folliculocystic and collagenous hamartoma (FCCH) is a rare cutaneous manifestation characterized by the presence of single plaques studded with comedo-like openings and cysts. Although its pathophysiology is still unknown, it has generally been described in men with tuberous sclerosis complex (TSC). We report a case of a one-year-old child with two FCCH in the abdominal wall associated with TSC. In our case, a TSC2 mutation was identified.