Trocar localisation for robot-assisted vitreoretinal surgery.

PURPOSE: Robot-assisted vitreoretinal surgery provides precise and consistent operations on the back of the eye. To perform this safely, knowledge of the surgical instrument's remote centre of motion (RCM) and the location of the insertion point into the eye (trocar) is required. This enables the robot to align both positions to pivot the instrument about the trocar, thus preventing any damaging lateral forces from being exerted. METHODS: Building on a system developed in previous work, this study presents a trocar localisation method that uses a micro-camera mounted on a vitreoretinal surgical forceps, to track two ArUco markers attached on either side of a trocar. The trocar position is the estimated midpoint between the markers. RESULTS: Experimental evaluation of the trocar localisation was conducted. Results showed an RMSE of 1.82 mm for the localisation of the markers and an RMSE of 1.24 mm for the trocar localisation. CONCLUSIONS: The proposed camera-based trocar localisation presents reasonable consistency and accuracy and shows improved results compared to other current methods. Optimum accuracy for this application would necessitate a 1.4 mm absolute error margin, which corresponds to the trocar's radius. The trocar localisation results are successfully found within this margin, yet the marker localisation would require further refinement to ensure consistency of localisation within the error margin. Further work will refine these position estimates and ensure the error stays consistently within this boundary.

Poroid hidradenoma in the hand: A case report and systematic review.

Poroid hidradenoma (PH) is a rare benign neoplasm of the skin appendages. There are currently no guidelines for its management, and little information available regarding the natural history, treatment options, or outcomes. Systematic literature review identified 19 cases of isolated PH. Mean age at presentation was 54 years. Male to female ratio was 3:1, and the majority of cases were in the head and neck region. One-third of lesions were painful or tender. Sizes varied from 0.11 × 0.9 × 0.2 cm (digit) to 6 cm (presternal region). Twelve cases were treated by surgical excision, while the remainder were biopsy specimens. Follow-up was reported in five cases, with a median follow-up of 1 year. No cases of local invasion or spread have been reported, although there was one case of possible recurrence identified 8 years after surgical excision. The presented case is the first to identify a PH on the hand, represents the smallest lesion to date, and was successfully treated by excision. We suggest that PHs be treated by excision and followed up for 6 to 12 months. Given one case of potential (but unconfirmed) recurrence, and no report of malignant transformation, we suggest that narrow margins may be appropriate.

Aberrant Melan-A expression in atypical fibroxanthoma and undifferentiated pleomorphic sarcoma of the skin.

BACKGROUND: Atypical fibroxanthoma (AFX) is a distinctive clinicopathologic entity presenting on sun-damaged skin of the elderly. Its behavior is benign if strict diagnostic criteria are applied. Tumors showing invasion of deeper structures or perineural/lymphovascular invasion are best regarded as undifferentiated pleomorphic sarcoma of the skin. The diagnosis requires immunohistochemical studies to exclude melanoma, squamous cell carcinoma, angiosarcoma and leiomyosarcoma. METHODS: Two AFX and one undifferentiated pleomorphic sarcoma showing aberrant expression of Melan-A were identified. Clinical data were obtained and histopathological features, immunohistochemical profile and electron microscopy were assessed. RESULTS: All tumors arose on sun-damaged skin of elderly males. Two AFX showed pushing growth into superficial subcutis only. The undifferentiated pleomorphic sarcoma was characterized by infiltrative growth into galea as well as perineural invasion. Multifocal expression of Melan-A and MART-1 was largely limited to tumor giant cells in the absence of S100 or HMB-45 labeling. No melanosomes or premelanosomes were identified by electron microscopy. CONCLUSIONS: Aberrant expression of Melan-A and MART-1 in AFX and undifferentiated pleomorphic sarcoma of the skin represents an important diagnostic pitfall with potential for misdiagnosis as melanoma.

Sentinel lymph node biopsy in melanoma: The Oxford ten year clinical experience.

Sentinel lymph node biopsy (SLNB) has become an established investigation for assessing microscopic nodal metastasis in melanoma. The American Joint Committee on Cancer (AJCC) incorporates the sentinel node status in its staging criteria for melanoma. We present our clinical evaluation of performing SLNB in a single UK centre between 1998 and 2008. There were 697 patients with a mean age 53 years (range 13-92). We were able to surgically harvest at least one sentinel node in 694 patients of which 532 (76%) were negative. Of the 162 positive patients, 129 underwent further completion lymphadenectomy with 29 showing further pathologically positive nodes. At median follow up of 46 months, mortality from melanoma for SLN positive and negative patients was 32% and 4%, respectively. Disease recurrence was noted in 10% of the SLN negative group. Survival curves showed significant difference (p<0.001) in outcomes for patients grouped by Breslow thickness. Postoperative complications were noted in 6% of patients. No life-threatening complications were noted. Our results are comparable to other national and international studies. We await the outcomes of ongoing trials to assess the therapeutic value of SLNB for melanoma.

Solitary fibrous tumour of the face: a rare case report.

Solitary fibrous tumour is an uncommon neoplasm that arises predominantly from within the pleura. Extrapleural manifestation of solitary fibrous tumour, particularly in the head and neck area, is extremely rare. Here, we report a solitary fibrous tumour of the face in a 40-year old woman. The tumour was removed with a radiological combined approach, with embolisation of tumour blood vessels prior to excision. Eight months following surgery, the patient is well and free of disease.

Salvage of finger length in septicemic necrosis using 3 free flaps from a single anterolateral thigh donor site.

Severe septicemic necrosis can result in extremely debilitating morbidity for patients, often resulting in 4-limb amputation. Further operative procedures to improve both function and cosmesis can be fraught with complexity and complications. The ideal aim in such patients would be to maintain sufficient length and provide soft tissue cover in a single 1-step procedure. We present a novel case in which twin free flaps were used acutely to provide 3 separate skin paddles to cover 2 hand stumps from a single anterolateral thigh donor site, thus maintaining the optimum digit length for subsequent function. We believe that this is the first reported case of using 3 separate flaps from 1 single anterolateral thigh donor site to resurface and salvage digit length in both hands following septicemic necrosis. Detailed knowledge of the anatomy of the anterolateral thigh flap and an understanding of the perforator flap concept can allow others to further develop the many and versatile uses of this flap.

Traumatic neuroma: a late complication of otoplasty.

We report on the development of traumatic ear lobe neuromas as a late complication of bilateral otoplasty performed 16 years previously. To our knowledge, this is the first and only described case of traumatic neuromas arising as a late complication of otoplasty in the English literature. Traumatic neuroma should be considered in the differential diagnosis of any nodular lesions that develop within the external ear in patients who have had otoplasty or any other form of external ear surgery or trauma.