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Pityriasis rosea, is an acute self-limiting papulosquamous inflammatory disorder. It usually starts with a herald patch on the trunk and proximal extremities, followed by scaly oval patches that give them a “Christmas tree” appearance. The lesions may be associated with fever a rash. The disease can present as numerous morphologies such as papular, urticarial, lichenoid, and generalized that may be confused with other conditions such as secondary syphilis, seborrheic dermatitis, nummular eczema, pityriasis lichenoides chronica, tinea corporis, viral exanthems, lichen planus, and PR like eruption linked to particular drugs. We report a rare case of polymorphic pityriasis rosea in paediatric age group.

Ki-67 proliferative index (PI) scoring is measured by estimating the proportion of the number of active cell nuclei in hotspot regions within immunohistochemical (IHC) stained slides. It provides valuable information about the rate of proliferation in a tumour. Manual scoring of Ki-67 PI is laborious, time-consuming and often the victim of interobserver variability between pathologists. This motivated us to develop an AI-based method to automate Ki-67 PI scoring with the aim to improve the concordance of pathologists' inter-observability through aided diagnosis. We sourced 88 sequential cases of sarcomas for our study. We applied watershed algorithm to perform nuclear segmentation on 440 regions of interest (ROI). A study was conducted where three pathologists scored the Ki-67 PI on the ROIs with and without AI-assistance. Our study demonstrated great concordance between the pathologists scoring with AI-assistance. After AI assistance, inter-pathologist discordance was significantly reduced by 82.1 %

Malignant melanoma is an aggressive, notorious tumor showing great variability in morphological and immunohistochemical expression, thus commonly leading to an erroneous diagnosis. Within the melanoma group, amelanotic melanoma, with its wide clinical presentations, lack of pigmentation, and varied histological appearances, has taken on a new persona as a master masquerader. Use of immunohistochemistry in the diagnosis of malignant tumors, including melanoma, is primordial and indispensable. However, the problem gets compounded in scenario of aberrant antigenic expression. The present case posed multiple diagnostic challenges in form of atypical clinical presentation, variant morphology, as well as aberrant antigenic expression. Here, we present the case of a 72-year-old male who, upon his initial presentation, was thought to be sarcomatoid anaplastic plasmacytoma, but 5 months later another biopsy from a different site revealed the actual diagnosis of amelanotic melanoma.

Pancreatic neuroendocrine tumors are typically solid neoplasms but in rare instances may present as cystic lesions. Preoperative diagnosis of a cystic pancreatic lesion is challenging and requires a multidisciplinary and multimodal approach. We hereby describe an elderly female who came with complaints of abdominal lump. Radiologically, it appeared to be a pancreatic hydatid cyst located at the head of the pancreas, following which resection was done. Histopathological study of the lesion turned out to be a cystic pancreatic neuroendocrine tumor. Thus, we present this unique case due to its rarity and diagnostic challenge.

Background The incorporation of immunohistochemical markers in the analysis of small biopsy samples, as outlined in the fourth edition of the World Health Organization Blue books, represents a noteworthy advancement in the diagnosis of advanced-stage lung carcinoma. This improved the histological classification for poorly differentiated nonsmall cell lung carcinomas (NSCLCs), especially in small biopsy specimens. Despite challenges in obtaining viable cells from diminutive tumor samples, a focused immunohistochemical panel effectively distinguishes histological types in most NSCLC. This preserves tissue for subsequent molecular testing.

Malignant melanoma originates from melanoma cells, which derive from the neuroectoderm of the ectodermal mucosa. The chameleonic presentation of malignant melanoma, its often asymptomatic nature, the rarity of the lesion, the grim prognosis, and the imperative for highly specialized treatment are critical factors that merit careful consideration. Herein, we report a compilation of five cases of malignant melanomas occurring at unusual anatomical locations, which were initially misdiagnosed, which on careful analysis with the use of immuno-histochemical stains were correctly diagnosed as malignant melanoma.

Multiple primary malignancies are defined as two or more malignancies arising independently to each other in the same or different anatomical sites, while excluding the possibility of metastasis from the primary malignancy. Here, we present three cases, each with dual malignancies involving different anatomical locations.

Merkel cell carcinoma (MCC) is a rare primary neuroendocrine tumor of the skin. It has an aggressive biological behavior and shows early local and distant metastasis. Diagnosis of MCC is a challenge and requires confirmation by immunohistochemistry (IHC). However, metastasis of MCC to the stomach is extremely uncommon and is rarely reported in the literature. We hereby describe a patient with gastric metastasis of MCC, who presented with black tarry stool and was finally diagnosed on the basis of clinical history, histology, and IHC.

Adenomatoid tumor, a benign tumor of mesothelial origin, is seen most commonly in paratesticular tissue in males and uterus in females. Its incidence is extremely rare in the fallopian tube, with only few such case reports. In the present case, an incidental association of adenomatoid tumor of the fallopian tube with turbo-ovarian endometriosis and ipsilateral nonfunctioning kidney was seen. Intraoperatively, a small nodular lesion was seen over the tubal wall. On a detailed review of literature, we found very few cases of adenomatoid tumor of the fallopian tube. The other unique finding was the occurrence of intratumoral endometriosis within the adenomatoid tumor.