Variants of dermatofibroma--a histopathological study

Clinicopathologic Analysis of Dermatofibroma: A Retrospective Study of 165 Cases

Dermatofibroma (DF), also known as benign fibrous histiocytoma, is a common benign skin tumor whose clinicopathologic features and pathogenesis remain only partially understood. In this retrospective study, 165 cases of DF diagnosed between 2018 and 2024 were analyzed to characterize demographic, clinical, and histopathologic profiles. Data regarding patient age, gender, horizontal tumor size, anatomical location, and pathological subtypes were extracted from digital pathology archives. Statistical analyses revealed that male patients exhibited significantly larger horizontal tumor sizes compared to female patients (P = 0.027). Additionally, the tumor location was significantly associated with size, with lesions in the subcutaneous tissue showing larger mean horizontal dimensions than those in the reticular or papillary dermis (P = 0.032). These findings suggest that gender, tumor location, and pathological subtype are influential factors in DF growth, providing further insight into its clinical behavior and potential underlying mechanisms. These findings highlight the importance of considering patient gender and tumor location in the clinical management of DF, potentially guiding personalized treatment strategies and improving patient outcomes.

Uncommon Collision Tumors: Dermoscopic and Histopathological Features of Basal Cell Carcinoma Overlying Dermatofibroma

Dermatofibromas (DFs) represent prevalent benign fibrohistiocytic tumors, typically manifesting as solitary lesions. In the majority of cases, the clinical presentation and dermoscopic and histopathological features of DFs adhere to a characteristic profile. However, DFs may exhibit atypical clinical presentations and, more commonly, histologic attributes, posing challenges in differential diagnosis. Both DFs and basal cell carcinomas (BCCs) are frequently encountered cutaneous lesions, each characterized by distinct clinical and dermoscopic features and microscopic morphology. The simultaneous occurrence of these two entities within the same lesion is rare. DFs have been documented to form collision tumors in conjunction with a spectrum of benign and malignant lesions, encompassing not only BCC but also balloon cell nevus, squamous cell carcinoma (SCC), and melanoma. Alterations in the epidermis overlaying a DF range from simple hyperplasia to the proliferation of basaloid cells. Accurate diagnosis, leading to the complete excision of the lesion, is contingent upon the recognition of dermoscopic criteria, precluding misinterpretation as a benign lesion. We present two cases of collision tumors comprising DF and BCC. This case report underscores the paramount importance of dermoscopy and adherence to dermoscopic criteria in the assessment of collision lesions and the diagnostic process related to cutaneous malignancies.

Atrophic Dermatofibroma: A Case Report With Dermoscopic and Histopathological Correlation

Atrophic dermatofibroma (ADF) is a rare variant of dermatofibroma (DF). In this article, we report a case of an asymptomatic 44-year-old woman with a concerning atrophic skin lesion on her leg. Clinical examination and dermoscopy were not enough to confirm the diagnosis, so surgical excision with a histopathological report led to the final diagnosis of atrophic dermatofibroma and the reassurance of the patient. Atrophic dermatofibroma should be considered in the clinician's differential diagnosis of atrophic lesions. Despite its benign nature, more sinister pathologies must be ruled out.

Factors Contributing to the False Diagnosis of Misleading Dermatofibromas

BACKGROUND AND OBJECTIVES

Dermatofibromas (DFs) are common benign skin lesions with unclear etiology, possibly reactive or tumoral. This study aims to evaluate the incidence of DF misdiagnosis and to correlate histopathological findings with clinical interpretations.

METHODS

The extraction for this retrospective study was conducted from 8035 excisions performed between 2016 and 2022 by 9 physicians. A total of 50 cases with conclusive histopathological diagnoses of DF and 33 clinical cases of DF were identified. A p value of < 0.05 was considered statistically significant.

RESULTS

The clinical arm included 33 cases, with 7 having DF in the differential diagnosis. The mean age for a confident DF diagnosis was 57.86 years, compared to 44.35 years for a probable diagnosis (p = 0.023). Diagnosis accuracy was 69% for certain cases versus 43% for probable cases. DF on legs had higher clinical uncertainty, 6/7 versus 9/26 (p = 0.016). In the histopathological arm of 50 patients, lesions on lower extremities had higher correct diagnosis rates (p = 0.024) and were least accurate on the torso (p = 0.009).

CONCLUSIONS

DF can pose a challenge even for experienced clinicians. Location is crucial as DF may escape diagnosis in less common areas. Patients' age and physician's expertise induce uncertainty.

Multiple Eruptive Dermatofibromas: A Case Series and Review of Diagnostic Challenges and Systemic Associations

Multiple eruptive dermatofibromas (MEDF) is a rare dermatological condition characterized by the sudden appearance of multiple benign skin lesions, often associated with systemic or autoimmune conditions. This case series describes three female patients with MEDF, highlighting their distinct clinical features and systemic associations. Diagnoses were confirmed through consistent histopathological findings, demonstrating the importance of integrating clinical, dermoscopic, and histopathological evaluations in diagnosing MEDF. The differential diagnosis included other dermatological conditions with overlapping features, which were excluded based on clinical and pathological findings. This report emphasizes the potential role of immune dysregulation and genetic predisposition in MEDF pathogenesis. It underscores the need for further research to understand its mechanisms better, improve diagnostic accuracy, and establish standardized management approaches.

Evaluation of Very-High-Frequency Ultrasound Imaging Characteristics of Dermatofibroma

Background

Dermatofibroma (DF) is one of the common dermatosis, which is so challenging to diagnose that its misdiagnostic incidence is quite high. The very-high-frequency (VHF) ultrasound is particularly relevant to the diagnosis of DF. Herein, we analyze the sonographic features and application value of VHF ultrasound in the diagnosis of DF.

Methods

Clinical data from 153 patients with pathologically confirmed DF from January 2019 to December 2023 were retrospectively analyzed using high-resolution VHF ultrasound, including size, location, shape, edge, boundary, interior echo, blood supply and so on.

Results

The VHF sonographic features of DF showed that the maximum diameter of the lesions was about 7.29 ±2.85 mm (mean ± standard deviation). In addition, most lesions were located in the middle and lower part of dermis (49%), with ill-defined (84%) and irregular shape (51%), 19% of which were serrated. Forty-four percent of lesions were hypo-echoic and heterogeneous, and 8% were complicated with calcifications. Nineteen percent of lesions presented as thickened dermal epidermal junction. Dermatofibroma are mostly hypovascular on color Doppler ultrasound. Forty-three percent of lesions were detected with punctate dotted blood flow signals. The correlation analysis showed blood flow classification and maximum diameter were not relevant.

Conclusion

The DF based on VHF ultrasonographic findings is characteristic, such as <10mm, ill-defined, located in the dermis, thickened DEJ, serrated shape, punctute or no flow on Doppler, which provide crucial indicators for differential diagnosis, potentially reducing the rate of DF misdiagnosis.

Clinicopathologic and molecular study of superficial CD34-positive fibroblastic tumours mimicking atypical fibrous histiocytoma (dermatofibroma)

AIMS

Superficial CD34-positive fibroblastic tumour (SCD34FT) is an uncommon but distinctive low-grade neoplasm of the skin and subcutis that shows frequent CADM3 expression by immunohistochemistry (IHC). In this study, prompted by an index case resembling 'atypical fibrous histiocytoma (FH)' that was positive for CADM3 IHC, we systematically examined a cohort of tumours previously diagnosed as 'atypical FH' by applying CADM3 and fluorescence in situ hybridization (FISH) for PRDM10 rearrangement, to investigate the overlap between these tumour types.

METHODS AND RESULTS

Forty cases of atypical FH were retrieved, including CD34-positive tumours (n = 20) and CD34-negative tumours (n = 20). All tumours were stained for CADM3. All CADM3-positive tumours were evaluated by FISH to assess for PRDM10 rearrangement. Eleven CD34-positive tumours (11/20, 55%) coexpressed CADM3 and were reclassified as SCD34FT. None (0/20) of the CD34-negative atypical FH were CADM3-positive. Reclassified SCD34FT (10/11) arose on the lower extremity, with frequent involvement of the thigh (n = 8). Features suggestive of atypical FH were observed in many reclassified cases including variable cellularity, spindled morphology, infiltrative tumour margins, collagen entrapment, epidermal hyperpigmentation, and acanthosis. Variably prominent multinucleate giant cells, including Touton-like forms, were also present. An informative FISH result was obtained in 10/11 reclassified tumours, with 60% (6/10) demonstrating PRDM10 rearrangement.

CONCLUSION

A significant subset of tumours that histologically resemble atypical FH, and are positive for CD34, coexpress CADM3 and harbour PRDM10 rearrangement, supporting their reclassification as SCD34FT. Awareness of this morphologic overlap and the application of CADM3 IHC can aid the distinction between SCD34FT and atypical FH.

Hemosiderotic Dermatofibroma in a Filipino Male

Dermatofibroma (DF) is a common, benign fibrohistiocytic tumor with unknown pathogenesis. There are multiple uncommon histologic variants of DF reported in literature, one of which is hemosiderotic DF. It can variably present as a pigmented papule or nodule commonly located on the lower extremities. Hemosiderotic DF remains to be underreported in the Philippines despite the widely available dermatopathology services in the country.

The use of ectopic volar fibroblasts to modify skin identity

Skin identity is controlled by intrinsic features of the epidermis and dermis and their interactions. Modifying skin identity has clinical potential, such as the conversion of residual limb and stump (nonvolar) skin of amputees to pressure-responsive palmoplantar (volar) skin to enhance prosthesis use and minimize skin breakdown. Greater keratin 9 (KRT9) expression, higher epidermal thickness, keratinocyte cytoplasmic size, collagen length, and elastin are markers of volar skin and likely contribute to volar skin resiliency. Given fibroblasts' capacity to modify keratinocyte differentiation, we hypothesized that volar fibroblasts influence these features. Bioprinted skin constructs confirmed the capacity of volar fibroblasts to induce volar keratinocyte features. A clinical trial of healthy volunteers demonstrated that injecting volar fibroblasts into nonvolar skin increased volar features that lasted up to 5 months, highlighting a potential cellular therapy.

Dermatoscopic shiny white structures in benign cutaneous tumours

The dermatoscopic characteristics of shiny white structures (SWS) in malignant skin tumours are well described, but data on benign skin neoplasms are scarce. To evaluate the dermatoscopic features of SWS in common benign tumours, we reviewed our database for histopathologically confirmed cases. Dermatoscopic images were evaluated for the presence of any type of SWS. Images with SWS were further analysed for their quantity, distribution and shape. Of 2420 evaluated benign tumours, 357 (14.8%) displayed SWS. The highest frequencies were observed in pyogenic granuloma (n = 62/100; 62%), angioma (n = 63/113; 55.8%) and adnexal tumours (n = 42/84; 50%). The lowest frequency was found in common naevi (n = 16/1032; 1.6%) and solar lentigo (n = 0). The presence of SWS was not associated with sex or anatomical location. SWS were usually diffuse and multiple. SWS may be present in a broad spectrum of benign tumours and therefore they should not be considered as de facto indicators of malignancy.

Giant thigh hemosiderotic/aneurysmal dermatofibroma: Case report with radiologic-pathologic correlation

Hemosiderotic/aneurysmal variant of dermatofibroma (DF) is infrequent and may be misdiagnosed with malignant lesions. We report the case of a giant (7.6cm) subcutaneous hemosiderotic/aneurysmal DF (H/ADF) of the thigh in a 53-year-old female patient. Internal arterial and venous hypervascularity was seen by spectral Doppler ultrasound. Magnetic resonance image showed a discrete homogeneous hypointense in T1-weighted images (WI) and T2-WI mass, with hyperintense areas in fat-suppressed T2-WI. The histology revealed a monotonous fusocelular proliferation without atypia, positive for CD163, factor XIIIa and CD10. Widely distributed hemosiderin pigment and two blood-filled pseudovascular spaces lacking endothelial lining were present. H/ADF was diagnosed. The mass was removed but surgical margins were affected. The patient did not present local relapse or distant metastasis. H/ADF are unusual cutaneous soft tissue tumours that can be clinically, radiologically and histopathologically confused with malignant lesions such as melanomas, vascular lesions or sarcomas, especially in giant cases.

"Unusual Presentation of Epitheloid Dermatofibroma- Rare Case Report"

Dermatofibroma is a commonly occurring cutaneous entity usually centered within the skin's dermis. Dermatofibromas are referred to as benign fibrous histiocytomas of the skin, superficial/cutaneous benign fibrous histiocytomas, or common fibrous histiocytoma. These mesenchymal cell lesions of the dermis clinically are firm subcutaneous nodules that occur on the extremities in the vast majority of cases and may or may not be associated with overlying skin changes. A 20 years old male presented to ENT OPD, at a private hospital, with complaints of a huge mass over right side of face since 15 years, which was slowly growing and not associated with pain. On clinical examination, hard, non tender, lobulated cauliflower like mass located over right side of face extending from right side temporal region to upper border of mandible from superior to inferior. From anterior to posterior it was extending from lateral 1/3rd of forehead and covering lateral canthus of right eye upto right side tragus. We have taken incisional biopsy which was suggestive of dermatofibroma. Then surgery was performed with patient's consent. Excision with 1 cm free margin was done. Raw area was covered with full thickness skin grafting and advancement flap. We found no recurrence till date. Dermatofibroma in the head and neck region is less common and often present a difficult differential diagnosis like Dermatofibrosarcoma protuberans, Kaposi Sarcoma, Basal cell carcinomas. The aim of case report is to represent case of dermatofibroma of epitheloid variety which is unusual in size.

Perforating Fibrous Histiocytoma Mimicking Keratoacanthoma: A Case Report

A 31-year-old male presented with a firm, well-demarcated, erythematous, crateriform, and ulcerated nodule in the left lumbar region, which persisted for 3 months. Clinically, a keratoacanthoma was suspected. The histological analysis was consistent with perforating fibrous histiocytoma, a rare histopathologic variant of fibrous histiocytoma. To our knowledge, this is the third case reported in the literature.

High-Frequency Ultrasound Imaging to Distinguish High-Risk and Low-Risk Dermatofibromas

BACKGROUND

Dermatofibroma has various pathological classifications, some of which pose a risk of recurrence and metastasis. Distinguishing these high-risk dermatofibromas based on appearance alone can be challenging. Therefore, high-frequency ultrasound may provide additional internal information on these lesions, helping to identify high-risk and low-risk dermatofibroma early.

METHODS

In this retrospective study, 50 lesions were analyzed to explore the correlation between clinical and high-frequency ultrasound features and dermatofibroma risk level. Based on their pathological features, the lesions were divided into high-risk (n = 17) and low-risk (n = 33) groups. Subsequently, an identification model based on significant high-frequency ultrasound features was developed.

RESULTS

Significant differences were observed in the thickness, shape, internal echogenicity, stratum basal, and Doppler vascular patterns between the high-risk and low-risk groups. The median lesion thickness for the high-risk dermatofibroma group was 4.1 mm (IQR: 3.2-6.1 mm), while it was 3.1 mm (IQR: 1.3-4.2 mm) for the low-risk dermatofibroma group. In the high-risk dermatofibroma group, irregular morphology was predominant (70.6%, 12/17), the most common being dermis-to-subcutaneous soft tissue penetration (64.7%, 11/17), and heterogenous internal echogenicity was observed in the majority of cases (76.5%, 13/17). On the other hand, regular morphology was more prevalent in the low-risk dermatofibroma group (78.8%, 26/33), primarily limited to the dermis layer (78.8%, 26/33), with homogeneous internal echogenicity also being prevalent in the majority of cases (81.8%, 27/33). Regarding the Doppler vascularity pattern, 69.7% (23/33) of low-risk dermatofibromas had no blood flow, while 64.7% (11/17) of high-risk dermatofibromas had blood flow.

CONCLUSION

High-frequency ultrasound is crucial in distinguishing high-risk and low-risk dermatofibromas, making it invaluable for clinical management.

Papular Umbilicated Granuloma Annulare in a Patient With Systemic Lupus Erythematosus

Granuloma annulare (GA) is characterized by palisading granuloma, which is histopathologically distinguished by histiocytes arrayed in a palisade configuration encircling insoluble entities associated with degenerated collagen fibrils. The present case demonstrated multiple cutaneous papules showing palisading granuloma in a patient with SLE. A 39-year-old woman has been taking oral prednisolone daily, hydroxychloroquine sulfate, and belimumab for systemic lupus erythematosus (SLE). A few papules appeared on the lateral side of the left arm and gradually increased around both sides. Physical examination found multiple firm skin-colored papules ranging in diameter from 2 to 3 mm on both forearms. Some of the papules had umbilicated tops. Histopathological examination showed degenerated collagen fibers with mucin deposition surrounded by histiocyte infiltrates in the dermis. These findings are characteristic of palisading granuloma. There are several GA variants, such as generalized, subcutaneous, and perforating GA. We considered several possibilities of the mechanisms underlying characteristic histological changes; atypical generalized GA variants, dermatofibroma, and granuloma associated with cutaneous vasculitis. We made the final diagnosis of papular umbilicated GA in the context of SLE.

Hemosiderotic Xanthelasmas. A New Clinicopathological Variant of Xanthelasma Palpebrarum or a Localized Variant of Xanthosiderohistiocytosis of the Eyelids?

ABSTRACT

Xanthelasma palpebrarum represent the most common subtype of cutaneous plane xanthomas. Xanthosiderohistiocytosis is considered a rare variant of xanthoma disseminatum, with only 4 cases reported to date. We report the case of a man with progressive pigmented lesions on the 4 eyelids that could correspond to hemosiderotic xanthelasmas or a localized variant of xanthosiderohistiocytosis.

Pulmonary Metastasising Aneurysmal Fibrous Histiocytoma: A Case Report, Literature Review and Proposal of Standardised Diagnostic Criteria

An aneurysmal fibrous histiocytoma is a rare cutaneous soft-tissue tumour which accounts for approximately 0.06% of all dermatopathologies. Metastasis is exceedingly uncommon, to the point that there have only been eight reported cases in the scientific literature. We present the case of a 25-year-old male with a primary aneurysmal fibrous histiocytoma located in the nuchal region which exhibited rapid growth and abrupt ulceration over a short time span and showed signs of locoregional aggressive infiltration. A subsequent histopathological analysis confirmed the presence of diffuse solid and cystic pulmonary metastases. Further genetic sequencing verified LAMTOR1-PRKCD fusion. This case report seeks to review the existing literature on aneurysmal fibrous histiocytoma, discuss the challenges of differential diagnosis and propose standardised diagnostic criteria.

Challenging Patterns of Atypical Dermatofibromas and Promising Diagnostic Tools for Differential Diagnosis of Malignant Lesions

Dermatofibroma (DF) or fibrous histiocytoma is one of the most frequent benign cutaneous soft-tissue lesions, characterized by a post-inflammatory tissue reaction associated with fibrosis of the dermis. Clinically DFs have a polymorphous clinical aspect from the solitary, firm, single nodules to multiple papules with a relatively smooth surface. However, multiple atypical clinicopathological variants of DFs have been reported and, therefore, clinical recognition may become challenging, leading to a more burdensome identification and sometimes to misdiagnosis. Dermoscopy is considered an important tool in DFs diagnosis, as it improves diagnostic accuracy for clinically amelanotic nodules. Although typical dermoscopic patterns are most frequently seen in clinical practice, there have also been some atypical variants described, mimicking some underlying recurrent and sometimes harmful skin afflictions. Usually, no treatment is required, although an appropriate work-up may be necessary in specific cases, such as in the presence of atypical variants or a history of recent changes. This narrative review's aim is to summarize current evidence regarding clinical presentation, positive and differential diagnosis of atypical dermatofibromas and also to raise awareness about the importance of specific characteristics of atypical variants to better differentiate them from malignant conditions.

Clinical and pathological studies of eight cases of lipidized fibrous histiocytoma

Lipidized fibrous histiocytoma (FH) is a rare type of FH. The present study aimed to describe the clinical and pathological features of lipidized FH. A total of eight patients diagnosed with lipidized FH were retrospectively reviewed in the present study. The cohort included three male and five female patients (male to female ratio, 1.7:1) with a mean age of 48 years (range, 38-62 years). In total, four tumors were located on the buttock, three on the lower leg and one on the forearm. Histological, lipidized FH showed a wide spectrum. Some cases included prominent stromal hyalinization and hyalinized vessels with scant lipid-laden histiocytes. Other cases exhibited the prominent lipid-laden histiocytes and scant stromal hyalinization. Overall, lipidized FH must be differentiated from other benign and malignant tumors, taking into account the therapeutic and prognostic differences between these different entities.

Keloidal dermatofibroma: Clinicopathological comparison of 52 cases with a series of 2077 other dermatofibromas

Dermatofibroma is a common benign skin lesion with a contested etiology: some believe it is a neoplasm while others propose minor injuries initiate it. Many dermatofibroma variants have been described, including keloidal dermatofibroma, which is unusual by bearing keloidal collagen. Keloidal dermatofibroma was first described in 1998 and only 15 cases have been reported. Since keloids are driven by skin injuries, the existence of keloidal dermatofibroma has been suggested to support the injury hypothesis of dermatofibroma etiology. To better understand keloidal dermatofibroma characteristics and gain clues regarding dermatofibroma etiology, consecutive keloidal dermatofibroma cases (n = 52) and dermatofibroma without keloidal collagen (n = 2077) that were histopathologically diagnosed in 2016-2019 were identified from the records of a Japanese dermatopathology laboratory and compared in terms of demographic, clinical, and histopathological characteristics by univariate analyses. Compared to other dermatofibromas, keloidal dermatofibromas occurred more frequently on the forearm and hand (P < 0.0001 and 0.0019), especially the wrist dorsum, and in the superficial skin layer (P < 0.0001). Keloidal dermatofibromas also demonstrated more cellularity and hemorrhage (both P < 0.0001). Correlation analyses between keloidal collagen amount and keloidal dermatofibroma size (a proxy of time-since-onset) did not support the notion that keloidal collagen deposition and keloidal dermatofibroma formation are triggered simultaneously. Recent injury, as indicated by fresh hemorrhage, was equally common in putatively older and younger keloidal dermatofibromas. Thus, keloidal collagen in keloidal dermatofibromas could be due to injury to preexisting dermatofibromas, which suggests that the keloidal dermatofibroma entity does not prove the injury hypothesis. Commonalities between keloids and keloidal dermatofibromas suggest a link between genetics, provocative events that induce myofibroblast differentiation, and keloidal collagen production.

Clinicopathologic Features of Facial Dermatofibromas, a Cohort Study, and a Systematic Review of Literature

BACKGROUND

Dermatofibromas are common skin tumors that typically occur on the extremities and trunk and demonstrate benign behavior, frequent recurrences, and very rare metastasis. Facial dermatofibromas are rare and not well studied . We analyzed clinicopathologic features of facial dermatofibromas.

DESIGN

Considering the rarity of the condition, we conducted a cohort study and a systematic review. We queried medical records of a single tertiary care center for dermatofibromas from January 1, 2000, to July 1, 2021. A systematic review of multiple databases was conducted through October 27, 2021, to include studies reporting facial dermatofibromas. Random-effects meta-analysis was used to estimate pooled odds ratio and proportions with associated 95% confidence interval (CI).

RESULTS

The cohort study identified 2858 cases of dermatofibromas, of which, 23 cases from 18 patients were on the face (1%). The mean age was 52.7 ± 17.8 years. Fifty-six percent of the cases were women. The most common location was the forehead (6 cases). The mean follow-up was 54 months. Forty-four percent of the cases had subcutaneous involvement, and 39% were the cellular type. Margins were positive in 89% of the cases, recurrence rate was 22%, and no metastases were observed. The systematic review included 10 studies (119 patients). Meta-analyses showed that facial dermatofibromas were 2% of all dermatofibromas (95% CI: 1%-3%). The local recurrence rate was 14% (95% CI: 6%-26%). Facial dermatofibromas with subcutaneous involvement were more likely to recur [odds ratio 4.53 (95% CI: 1.12-18.24)]. Before histopathologic examination, clinical differential diagnosis included dermatofibromas in only 9% of the cases (95% CI: 2%-19%).

CONCLUSION

Facial dermatofibromas are rare and are difficult to fully excise. Cellular type and subcutaneous or muscular involvement are common in these cases and tend to have higher local recurrence rate than other nonfacial dermatofibromas. Wider excisions might be necessary for complete excision.

Granular cell dermatofibroma: A potential diagnostic pitfall

Dermatofibroma, also known as "fibrous histiocytoma", is one of the most common cutaneous soft-tissue tumours. Many variants of dermatofibromas have been described and knowledge of these variations is important to avoid a misdiagnosis of a possibly more aggressive tumour. Histological features of different variants can coexist in the same lesion, but typical common fibrous histiocytoma features are generally found, at least focally, in all cases. However, when cellular changes make up the majority of the lesion, the histopathological diagnosis can become more complex and requires immunohistochemical investigations for a correct nosographic classification. We report on the case of a cutaneous fibrous histiocytoma, "granular cell" variant, found on the left leg of a 74- year-old woman.

Hyperpigmented Nodular Dermatofibroma: Two Cases Report and Brief Literature Review

BACKGROUND: Dermatofibroma (DF) is a common benign skin tumor (Benign Fibrous Histiocytoma) that mostly affects the extremities with a tendency to occur more often in older females than males. It usually presents as a slow growing small brown dome shape papule on the extremities. DF has a chronic nature and can sometimes regresses spontaneously. Dermoscopy is essential in the evaluation of DF to help differentiate it with other skin tumors. The gold standard evaluation for diagnosis of DF is biopsy with histopathologic examination. Removal of DF is often due to cosmetic factors, with surgical excision being the preferred method for removal. DF has an excellent prognosis. CASE REPORT: We present two case reports of women with hyperpigmented nodules on the lower extremity. Dimple sign was positive. From dermoscopic study showed a pigment network and central white patch pattern. On histologic examination revealed proliferation of fibroblast such as spindle cells as a storiform pattern and hyperplastic epidermis with hyperpigmentation of the basal layer. Based on clinical features, dermoscopy and histopathological evaluation, the diagnosis of DF was established. Both patients were perform surgically excision and have a good result. CONCLUSION: Dermatofibroma is benign fibrous histiocytoma that represents one of the most common skin tumours. Nodular hyperpigmented dermatofibroma is a clinical variant of Dermatofibroma which can be treated with surgical excision with good prognosis.

Granular Cell Dermatofibroma: When Morphology Still Matters

Dermatofibroma, also known as "fibrous histiocytoma", is one of the most common cutaneous soft-tissue tumors. Many variants of dermatofibromas have been described, and knowledge of these variations is important to avoid misdiagnosis of a possibly more aggressive tumor. Histological features of different variants can coexist in the same lesion, but typical common fibrous histiocytoma features are generally found, at least focally, in all cases. However, when cellular changes make up the majority of the lesion, the histopathological diagnosis can become more complex and requires immunohistochemical investigations for correct nosographic classification. We present the case of a cutaneous fibrous histiocytoma, "granular cell" variant, found on the left leg of a 74-year-old woman.

Atrophic Dermatofibroma: A Unique Dermatofibroma Variant

Dermatofibromas are benign skin tumors with several variants, including the rare, uncommonly described atrophic dermatofibroma. To the best of our knowledge, there are currently 105 reported cases of atrophic dermatofibromas in the literature. This variant typically presents as a flat or depressed macule whose color can range from brown to white to red; in contrast to classic dermatofibromas that typically occur on the legs, atrophic dermatofibromas have a tendency to occur on the upper back and arms. An atrophic dermatofibroma can be clinically diagnosed; however, given the broad spectrum of clinical features of this lesion, a biopsy may be required. Characteristic pathologic features include epidermal acanthosis, basilar hyperpigmentation, fibroblast hyperplasia, and decreased or absent elastic fibers within the lesion. The pathogenesis of this lesion is not yet fully understood; however, it has been postulated that the loss of elastic fibers plays a key role in its development and characteristic atrophic appearance. We present the cases of two men with biopsy-confirmed atrophic dermatofibromas: a 47-year-old man with a pigmented macule on the right upper back and a 68-year-old man with an erythematous patch on the left posterolateral shoulder. The clinical and pathologic features of atrophic dermatofibromas are also summarized.

Hemosiderotic dermatofibroma mimicking melanoma: A case report and review of the literature

Hemosiderotic dermatofibroma (HDF) often mimics melanoma clinically. A definite diagnosis relies on histopathological evaluation and immunohistochemistry. As it can progress to aneurysmal dermatofibroma (ADF), complete excision is recommended.

A rare case of atrophic dermatofibroma with dermoscopic findings

BACKGROUND

Dermatofibroma, also known as cutaneous benign fibrous histiocytoma, is a common skin tumour.

AIM

The aim of this paper was to present a rare variant of dermatofibroma, atrophic dermatofibroma, emphasizing histopathological and dermoscopic features.

PATIENTS/METHODS

A case of atrophic dermatofibroma in a female patient with the characteristic histopathological features and newly demonstrated dermoscopic findings is presented.

RESULTS

A 54-year-old female presented with a depressed reddish lesion on the back showing histopathological findings of atrophic dermatofibroma. The dermoscopy of the lesion revealed a peripheral pigment network surrounding a pink-reddish colouration around a central whitish scar-like patch with white-yellow scales which was not an exact match with the description in the literature.

CONCLUSION

Atrophic dermatofibroma is a rare variant that presents as an atrophic, depressed skin lesion which can easily be overlooked. Atrophic dermatofibroma should be considered in the differential diagnoses of atrophic, depressed lesions on the upper body of middle-aged women. The case of atrophic dermatofibroma presented here showed typical histopathologic findings with atypical dermoscopic features.

Positive MITF and NKI/C3 Expression in Cellular Neurothekeoma and Dermatofibroma

BACKGROUND

Cellular neurothekeoma (CNT) is a benign mesenchymal tumor with uncertain cellular differentiation. Studies have found evidence of myofibroblastic differentiation and possible relation to dermatofibromas (DFs). As microphthalmia transcription factor (MITF) and NKI/C3 stains are routinely positive in CNT, we compared expression patterns of both markers in CNT and DF to assess their relationship.

MATERIALS AND METHODS

We assessed cases of CNT (n=25) and DFs (n=35) for histopathologic characteristics and MITF and NKI/C3 expression. Immunostaining results were classified as negative, focally positive (<50%), and diffusely positive (>50%). At least 1 additional melanocytic marker was assessed in each case of CNT.

RESULTS

Both DFs and CNTs showed a female predilection and a wide age range. Immunostaining in CNTs for MITF was positive in the vast majority (focal 68%, diffuse 24%), as was NKI/C3 (focal 72%, diffuse 24%). All DFs were MITF positive (diffuse 74%, focal 26%), and most DFs were NKI/C3 positive (focal 57%, diffuse 3%).

CONCLUSION

CNT and DF share demographic, histopathologic, and immunohistochemical features, including shared expression of MITF and NKI/C3, especially cellular DF.

Two cases of adenodermatofibroma

Dermatofibromas (DF) are common skin lesions composed of a dermal proliferation of fibroblasts and histiocytes. Among the variants of DFs, adenodermatofibroma are characterized by a dense proliferation of fibroblasts and histiocytes admixed with entrapped dilated glandular structures. We report two additional cases of adenodermatofibromas, review the literature, theorize on the histopathogenesis of this variant, and suggest that there are different patterns among adenodermatofibromas, from primarily cystic to primarily glandular.

Cellular Dermatofibroma: Clinicopathologic Review of 218 Cases of Cellular Dermatofibroma to Determine the Clinical Recurrence Rate

BACKGROUND

Cellular dermatofibromas, a variant of dermatofibroma, are reported to recur at rates of 26% to 50%.

OBJECTIVE

To determine whether there are distinct clinical or histological differences between cellular dermatofibromas that recur versus those that do not. To determine recurrence rates in a real-world clinical setting.

MATERIALS AND METHODS

A retrospective analysis of the medical records and skin biopsies of cellular dermatofibroma in the University of Utah Health system between December 2011 and 2016. Clinical and dermatopathological features were evaluated to find distinct differences between the cellular dermatofibromas that recurred compared with those that did not.

RESULTS

There were no significant differences in histology between the primary lesions in recurrent and nonrecurrent cases. One factor that seemed to be associated with a greater likelihood of recurrence was an initial lesion size greater than 1 cm. The authors' data suggest that if the margins are involved on initial biopsy, there is a 10% chance of recurrence. This percentage is far less than the 26% to 50% reported in the past literature.

CONCLUSION

If a patient presents with a cellular dermatofibroma larger than 1 cm and positive margins at initial biopsy, a careful discussion should be had between the provider and patient about the low risk of local recurrence.

Hemosiderotic Dermatofibroma: A Rare and Atypical Variant Capable of Clinically Resembling Melanoma

A dermatofibroma (DF) is a common, benign tumor composed of fibroblastic and histiocytic cells. DF presents clinically with several different reported variants. One rare variant is hemosiderotic DF (HDF), which is made up of small blood vessels and hemosiderin deposits. HDF can be indistinguishable, clinically, from melanoma, making the use of other pathological tools crucial in the diagnosis. We report the case of a 25-year-old male medical student from the Caribbean who presented to our clinic with a single asymptomatic pigmented cystic lesion on his left posterior calf. The cystic lesion was excised surgically. Histopathology examination of the excised mass revealed a moderately cellular, poorly demarcated, dermal, fibrohistiocytic proliferation. Pathology consultation confirmed a diagnosis of HDF.

A Rare Case of Atrophic Dermatofibroma Featuring Linear Skin Dimple

Dermatofibroma (DF) is a benign skin tumor that is well-known among dermatologists. We herein present a rare case of atrophic dermatofibroma presenting linear skin dimpling. The patient was a 25-year-old woman with a history of wild-type recessive dystrophic epidermolysis bullosa who had noticed linear concavity on her right lateral back 1 year before her initial presentation. Anetoderma, atrophic scar, localized morphea, or lupus erythematosus profundus were clinically suspected; however, a biopsy specimen from the dimpling lesion showed the fibrous and histiocytic tumor in the deep dermis. The spindle-to-rhomboid-shaped tumor cells were arranged with irregularly storiform pattern, and immunohistochemistry showed that the tumor cells were positive for factor XIIIa, and negative for CD34 and CD68. Elastica van Gieson staining showed an almost complete loss of elastic fibers, especially at the center of the lesion. The reduction of elastic fibers might have influenced the skin depression in this case. This rare case suggests the need to consider a subtype of DF in the differential diagnosis of dimpling skin lesions.

A Case of Atrophic Dermatofibroma Overexpressing Matrix Metalloproteinase-1

This case report describes the importance of considering this tumor as one of the differential diagnoses when we encounter a flat and/or atrophic and depressible lesion in the upper portion of the trunk.

Atrophic Dermatofibroma: A Comprehensive Literature Review

INTRODUCTION

An atrophic dermatofibroma is a benign fibrohistiocytic neoplasm. It typically presents as an asymptomatic patch with a depressed central area.

METHODS

The PubMed database was used to search the following words: atrophic, dermatofibroma, elastic and fibers. The relevant papers and their references generated by the search were reviewed. Images of the clinical and pathological features of two patients with an atrophic dermatofibroma are presented. In addition, a comprehensive review of the characteristics of this unique dermatofibroma is provided.

RESULTS

An atrophic dermatofibroma has been reported in 102 patients: 53 women, 11 men and 38 individuals whose gender was not provided. It typically appeared as an asymptomatic solitary patch with a central umbilication-most commonly on the shoulder or lower extremity or back-of women aged 48 years or older. Dermoscopy typically showed white scar-like patches; a patchy pigment network was also noted in some lesions. The pathology of an atrophic dermatofibroma has the same features that can be observed in a common fibrous dermatofibroma; there is acanthosis, basal layer hyperpigmentation, and induction of basal cell carcinoma-like features, hair follicle formation or sebaceous hyperplasia in the epidermis and a proliferation of spindle-shaped fibroblasts in the dermis. However, atrophic dermatofibromas also demonstrate depression of the central surface and thinning of the dermis; in many cases, the dermal atrophy is at least 50%. Elastic fibers are either decreased or absent. Similar to non-atrophic dermatofibromas, the immunoperoxidase profile of atrophic dermatofibromas is factor XIIIa-positive and cluster of differentiation 34 (CD34)-negative. The pathogenesis of atrophic dermatofibromas remains to be established.

CONCLUSION

An atrophic dermatofibroma is an uncommon benign variant of a dermatofibroma. The diagnosis can be suspected based on clinical features and dermatoscopic findings. A biopsy of the lesion will confirm the diagnosis. Periodic evaluation of the lesion site is a reasonable approach to the management of the residual tumor.

HL, Ruas CP, Jorge VM. Scanning electron microscopy of dermatofibroma

Dermatofibroma is a proliferation of spindle cells located in the dermis. We used scanning electron microscopy to examine two histologically confirmed lesions and observed preserved collagen bundles in the perilesional area. In the lesional area, the collagen was denser, without formation of bundles. Higher magnification showed collagen with mesh-like appearance similar to stretched tufts of cotton. Very high magnification evidenced the tufts of cotton and spindle cells measuring 2 to 12 microns.

Unusual presentation of dermatofibroma on the face: Case report

Dermatofibroma (DF; Benign Fibrous Histiocytoma) seldom presents on the face. We present an unusual case presentation of translucent nodule on the upper right cheek of the face which was diagnosed clinically as basal cell carcinoma. Physician should include DF in the differential of such lesions.

Dermoscopy of lipidised dermatofibroma: A morphological study of 13 cases

BACKGROUND/OBJECTIVES

The aim of this study was to evaluate the morphological findings of lipidised dermatofibromas under dermoscopic observation.

METHODS

Dermoscopic examination of 13 cases of lipidised dermatofibromas was performed to evaluate specific dermoscopic criteria and patterns.

RESULTS

The most frequently occurring dermoscopic features were as follows: (i) A yellowish homogenous pigmentation in all cases (100%); this pigmentation was total in 30.7%; (ii) White structures were seen in 46.1%, most of them were central white networks (38.4%); (iii) Pigment network was observed in 53.8%, most of them were peripheral delicate pigment networks (38.4%), but two cases showed an atypical pigment network; (iv) The presence of vascular structures was common (10 cases, 77%); (v) Regarding to dermoscopic patterns, five lipidised dermatofibromas (38.4%) showed a total yellowish homogeneous pattern; 38.4% an atypical pattern and 23.2% a 'central white network + peripheral delicate pigment network' pattern.

CONCLUSIONS

The dermoscopic recognition of a total yellowish homogeneous area or a yellowish colouration in the context of a dermatofibroma can be proposed to help suspecting a lipidised dermatofibroma.