CASE REPORT. Homogeneous blue pigmentation in dermatofibroma simulating a blue naevus

Dermoscopy of haemosiderotic/aneurysmal dermatofibroma: A morphological study of 110 cases

BACKGROUND

Haemosiderotic and aneurysmal dermatofibromas are uncommon and frequently misdiagnosed lesions, which can be considered as different histopathological stages of the same tumour. A dermoscopic diagnosis testing accuracy has not been performed for these tumours to date.

OBJECTIVES

To determine the diagnostic significance of dermoscopic structures and patterns associated with haemosiderotic/ aneurysmal dermatofibromas in a large series.

METHODS

Dermoscopic images of histopathologically proven cases of 110 haemosiderotic/ aneurysmal dermatofibromas and 501 other tumours were collected. The frequency, sensitivity, specificity, positive predictive value and negative predictive value of the dermoscopic structures and patterns associated with these lesions were calculated.

RESULTS

Haemosiderotic/ aneurysmal dermatofibromas are mostly symmetric lesions (86.5%), and a prominent homogeneous area was present in 100% of them. The presence of vascular structures was very common (86.4%), and dotted vessels were predominant (58.2%). Shiny white structures were seen in 85.5% of lesions, while a peripheral delicate pigment network was present in 69.1%. The most significant pattern was the one composed of a prominent homogeneous area and peripheral delicate pigment network, which showed a specificity of 100% with a relatively good sensitivity (69.1%). All the patterns containing a peripheral delicate pigment network showed very good specificities, positive predictive values and negative predictive values. Those patterns without a peripheral delicate pigment network showed the highest sensitivities, but they showed a significant overlap with other tumours, mainly with melanoma.

CONCLUSIONS

Dermoscopy is helpful in improving the diagnostic accuracy of haemosiderotic/ aneurysmal dermatofibromas. However, there is a considerable dermoscopic overlap between these tumours and melanoma, specifically when the peripheral delicate pigment network is absent.

Hemosiderotic dermatofibroma

We report a rare clinical case of hemosiderotic dermatofibroma in a 36-year-old female patient. The main dermatoscopic finding was represented by homogeneous blue-gray pigmentation. The aim of this report is to demonstrate the rarity of the lesion and the dermatoscopic importance it assumes by sharing a blue-gray homogeneous pattern with other benign and malignant lesions.

Typical and atypical dermoscopic presentations of dermatofibroma

BACKGROUND

Dermatofibroma is a common skin neoplasm that is usually easy to recognize, but in some cases its differentiation from melanoma and other tumours may be difficult.

OBJECTIVE

To describe the dermoscopic features of dermatofibromas, with special emphasis on the characteristics of atypical patterns, and to calculate pattern frequency according to the patients age and gender, anatomical site and histopathological subtype.

METHODS

Two groups of patients were consecutively seen, one with dermatofibromas that were surgically excised because of clinically and/or dermoscopically equivocal aspects or following patient request, and another with non-equivocal dermatofibromas. Each lesion was scored for previously reported global dermoscopic patterns and for additional features.

RESULTS

A typical pattern was observed in 92 of 130 (70.8%) lesions, whereas an atypical pattern, that we named the 'non Dermatofibroma (DF)-like' pattern, was seen in 38 of 130 (29.2%). Atypical dermatofibromas showed features reminiscent of different conditions, such as melanoma in 21(16.2%) cases, vascular tumour in six (4.6%), basal cell carcinoma in five (3.8%), collision tumour in three (2.3%) and psoriasis in three (2.3%). A significant association was found between the 'melanoma-like' pattern/'vascular tumour-like' pattern and males, whereas a trend was observed between the above-mentioned patterns and hemosiderotic/aneurysmal DFs. 'Peripheral pigment network and central white scar-like patch' pattern was found associated with females and classic histopathological variant of DF.

CONCLUSION

Dermatofibromas may display different morphological faces. The typical dermoscopic patterns allow a confident diagnosis, whereas a full surgical excision is always recommended in all doubtful cases.

Non-melanocytic mimics of melanocytic neoplasms

On histopathologic examination, many non-neoplastic conditions mimic benign or malignant neoplasms. Alternatively, some benign and malignant neoplasms can also mimic non-neoplastic lesions. This is true of all organ systemsskin is no exception. Examples of these mimickers can be found in skin lesions of almost all tissue types, including those that are melanocytic, lymphoid, epithelial, neural, vascular, neuroendocrine, and fibrohistiocytic. Melanocytic neoplasms are particularly important as it's challenging to differentiate them as being benign or malignant, and it's difficult to tell them apart from non-melanocytic neoplasms. This review illustrates examples of non-melanocytic lesions that disguise themselves as melanocytic.

Different dermoscopic faces of dermatofibromas

BACKGROUND

Central white scarlike patch and a delicate pigment network at the periphery is the typical appearance of dermatofibromas on dermoscopy.

OBJECTIVE

We aimed to analyze the different dermoscopic appearances of dermatofibromas.

METHODS

Fifty-two dermatofibromas with dermoscopic features different from the classic type, which were detected between May 2003 and July 2005, were evaluated.

RESULTS

Globules in the scarlike area (38.5%), linear/irregular crypts (26.9%), lentigo-like reticular pigmentation (23%), homogeneous blue-gray pigmentation (5.9%), and erythematous homogeneous area surrounding the white patch (3.8%) were the patterns observed. In addition, dermoscopic features of an atrophic variant of dermatofibroma are described, which was seen in one lesion (1.9%).

LIMITATIONS

None.

CONCLUSION

Dermatofibromas have various dermoscopic features. Among them, "linear, irregular crypts" is not unusual and is described in this study. Homogeneous bluish pigmentation on dermoscopy may be a possible clue for the diagnosis of hemosiderotic variants of dermatofibromas.