LITERATURE UPDATE
The resulting histological findings can be confusing but correlating them with the clinical and surgical history often reassures surgeons. Recognising these artefacts facilitates accurate diagnosis and promotes optimal patient care.
An Update and Review of Clinical Outcomes Using Immunohistochemical Stains in Mohs Micrographic Surgery for Melanoma Elgash M, Young J, White K, Leitenberger J, Bar A. Dermatol Surg. 2024 Jan 1; 50 (1): 9-15.
doi: 10.1097/DSS.0000000000003945.
Mohs micrographic surgery (MMS) provides optimal margin control through complete peripheral and deep margin assessment. The treatment of melanoma using MMS has historically been limited by difficulty in interpreting melanocytes using frozen sections. Immunohistochemical (IHC) staining, a technique whereby chromogen-tagged antibodies are used to detect antigens of interest, has revolutionised the surgical treatment of melanoma. This article provides an update and literature review of current IHC stains used in MMS for melanoma, their sensitivities and specificities, and clinical outcomes. A PubMed search was performed using keywords including
‘immunohistochemistry’, ‘staining’, and ‘Mohs surgery’.” Articles related to the use of IHC staining for the treatment of melanoma with MMS were included. Six IHC stains met the criteria
for the review including melanoma antigen recognised by T cells (MART- 1), SRY-related HMG-box (SOX10), microphthalmia-associated transcription factor, HMB-45, MEL-5, S-100, and preferentially expressed antigen in melanoma.
The adaptation of IHC methods to
frozen sections has enabled MMS to become a preferred treatment option for melanoma in special-site areas. Future studies are needed to standardise IHC techniques and to define best practices when using frozen section in the treatment of melanoma.
Deep Learning for Automated Segmentation of Basal Cell Carcinoma on Mohs Micrographic Surgery Frozen Section Slides Varra V, Shahwan KT, Johnson K et al. Dermatol Surg. 2025 Apr 1; 51 (4): 355-359. doi: 10.1097/ DSS.0000000000004501
Deep learning has been used to classify basal cell carcinoma (BCC) on
82
histopathologic images. Segmentation models, required for localisation of tumour on Mohs surgery (MMS) frozen section slides, have yet to reach clinical utility. The objective of this study is to train a segmentation model to localise BCC on MMS frozen section slides and to evaluate performance by BCC subtype.
The study included 348 fresh frozen tissue slides, scanned as whole slide images, from patients treated with MMS for BCC. BCC foci were manually outlined using the Grand Challenge annotation platform. The dataset was divided into 80% for training, 10% for validation, and 10% for the test dataset. Segmentation was performed using the Ultralytics YOLOv8 model.
Sensitivity was 0.71 for all tumours, 0.87 for nodular BCC, 0.79 for superficial BCC, 0.74 for micronodular BCC, and 0.51 for morpheaform and infiltrative BCC. Specificity was 0.75 for all tumours, 0.59 for nodular BCC, 0.58 for superficial BCC, 0.83 for micronodular BCC, and 0.74 for morpheaform and infiltrative BCC.
This study trained a segmentation model to localise BCC on MMS frozen section slides with reasonably high sensitivity and specificity, and this varied by BCC subtype. More accurate and clinically relevant performance metrics for segmentation studies are needed.
Follicular Lymphoma Detected in a Patient Undergoing Mohs Surgery: A Case Report Defty C, Krishna Y, Khan MAA, Sharma N, Tehrani H. Cureus. 2025 Jan 17; 17 (1): e77583. doi: 10.7759/cureus.77583. eCollection 2025 Jan.
Mohs surgery is performed by surgeons trained in detecting specific cutaneous malignancies, including basal cell carcinoma (BCC), squamous cell carcinoma (SCC), and dermatofibrosarcoma protuberans (DFSP). Mohs-trained surgeons are typically not holistic pathologists and may, when working in isolation, fail to identify lesions that are not of cutaneous origin. The presence of a second lesion adjacent to the primary lesion is always a possibility. Such a lesion may be misinterpreted as an extension of the identified primary lesion, leading to unnecessary surgery, or it may be overlooked, resulting in a diagnostic failure. There is an advantage to conducting Mohs surgery with the surgeon and histopathologist reviewing the frozen section slides together, as this approach can aid in the identification of rarer diagnoses.
Here, the authors describe the case of a female patient who underwent Mohs micrographic surgery (MMS) for a recurrent BCC located in the left preauricular area and medial helical rim of the pinna. The surgery involved two excisional stages. The first stage showed morphoeic BCC at all levels of all blocks. The second stage showed no BCC but revealed a dense inflammatory infiltrate. On further assessment by the consultant histopathologist, this infiltrate raised suspicion of possible lymphoma. Based on this consensus, no further Mohs excisional surgery was performed, and the surgical defect was closed. Formalin-fixed paraffin wax-embedded (FFPE) histological assessment and immunohistochemistry confirmed the diagnosis of cutaneous B-cell follicular lymphoma (FL). Thus, the incidental finding on the examination of fresh frozen MMS sections was correctly interpreted by the combined approach of the Mohs surgeon and pathologist, guiding appropriate and timely management for the patient.
Recurrence Rate for Melanoma Excised by Mohs Micrographic Surgery Without Immunostaining Vieira C, Jennings T, Renzi MA Jr, Lawrence N, Decker A. Dermatol Surg. 2022 May 1; 48 (5): 492-497. doi: 10.1097/DSS.0000000000003435.
Mohs micrographic surgery (MMS) is becoming increasingly popular for the treatment of cutaneous melanoma (CM) as multiple studies have demonstrated favorable outcomes for local recurrence and overall survival.
This study analyses the outcomes of non-invasive (NIM) and invasive melanomas (IM) using MMS with fresh frozen sections. The primary outcome was local recurrence. The secondary outcome was to identify mean surgical margins based on tumour type and location. Retrospective cohort study was undertaken of 224 cases of CM treated from 2006 to 2016 at a tertiary academic centre with MMS and fresh frozen sections by a single Mohs surgeon. The overall recurrence rate was 2.6% with a mean follow-up of 36.2 months. The recurrence rate for NIM versus IM was 1.6% and 7%, respectively. The mean margins for NIM and IM were 7.9 mm and 10.1 mm, respectively. These varied by tumour site and location.
This study supports the use of MMS in
the treatment of CM and highlights how narrower surgical margins for NIM of the head and neck can be achieved without increasing risk of local recurrence.
SEPTEMBER 2025
WWW.PATHOLOGYINPRACTICE.COM
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84
