Clear cell lesions in pathology: Histomorphologic approach to diagnosis

Apocrine and clear cell metaplasia in the gallbladder: the first finding in the medical literature

Apocrine metaplasia, specifically, involves the development of cells resembling those in apocrine glands, characterized by their distinctive cytoplasmic features. Apocrine metaplasia in the gallbladder represents a new and intriguing discovery, marking a significant milestone in medical literature. Furthermore, clear cell metaplasia is often observed in other organs like the cervix and has never been documented in the gallbladder. The coexistence of apocrine and clear metaplasia challenges existing paradigms surrounding gallbladder pathology, prompting a reevaluation of the underlying mechanisms that drive these cellular transformations.

Clear cell oral squamous cell carcinoma as a diagnostic conundrum: report of 2 rare cases

The occurrence of clear cell histologic sub-type of oral squamous cell carcinoma in the oral cavity is a distinct and exceedingly rare entity exhibiting aggressive behavior. To date, only 10 cases have been published in the literature. We describe 2 extremely rare cases, both presenting with swelling and ulcerated nodule-like proliferative growth in the mandible. Microscopically, sheets and lobules of neoplastic squamous epithelial cells showing clear cell differentiation were appreciated in both patients. Periodic acid-Schiff and mucicarmine revealed negative staining. Immunohistochemical (IHC) analysis for antibody for renal cell tumor marker CD 10 was immune-negative. The malignant clear cells in both cases showed intense positive reactions with IHC markers pan-cytokeratin and epithelial membrane antigen, confirming the diagnosis as a clear cell variant of oral squamous cell carcinoma (CCOSCC). The first patient was unwilling for treatment and eventually died within 2 months of the diagnosis. In the second patient, right hemi-mandibulectomy with level 1A and 1B lymph nodes was performed. Adjuvant chemotherapy with low-dose methotrexate was initiated. Follow-up after 2 months of surgery was uneventful. Current rare reports emphasize the significance of prompt and extensive diagnostic work-up of clear cell neoplasms, as the CCOSCC may be fatal.

A Comparison of Clear Cell Sarcoma to Jaw and Salivary Tumors Bearing EWS Fusions

OBJECTIVE

To review tumors identified as "clear cell sarcoma" in order to determine similarities to the rare EWS fusion positive jaw and salivary gland tumors clear cell odontogenic carcinoma (CCOC) and clear cell carcinoma of the salivary gland (CCC).

METHODS

PubMed was used to collect all reports of clear cell sarcoma (CCS). Search parameters were "clear cell sarcoma" and "CCS." References in the publications were screened and cross-referenced. Data extracted included demographic characteristics, presenting signs and symptoms, radiographic findings, histological and immunohistochemical features and known molecular/genetic aberrations.

RESULTS

Clear cell sarcoma has several similarities to CCOC and CCC. All three tumor types have similar histologic appearances including the presence of clear cells, as well as similar genetic profiles in that all harbor an EWSR1-CREB family fusions. Additionally, these tumors appear in soft tissue as well as bone, and can have a prolonged clinical course. CCS can appear anywhere in the body, including the head and neck region. All three tumors appear to have a predilection to women, although CCS may have a slight younger age of onset as compared to CCOC and CCC (3rd vs 5th decade of life, respectively).

CONCLUSION

Gaining a better understanding of the similarities and differences between these three tumors may lead to a better understanding of each one.

Top 10 Clear Cell Head and Neck Lesions to Contemplate

BACKGROUND

Optically clear cytoplasm may occur in neoplastic and non-neoplastic conditions, either as a characteristic feature of a disease entity or as a morphologic rarity, potentially creating diagnostic dilemmas in various organ systems. In the head and neck, clear cell change can occur in lesions of salivary, odontogenic, thyroid, parathyroid, or sinonasal/skull base origin, as well as in metastases to these regions.

METHODS

This review elaborates the top ten clear cell lesions in the head and neck, emphasizing their distinguishing histologic, immunohistochemical, and molecular attributes, and presents a rational approach to arriving at an accurate classification.

RESULTS

Cytoplasmic pallor or clearing may be caused by accumulations of glycogen, lipid, mucin, mucopolysaccharides, water, foreign material, hydropic organelles, or immature zymogen granules. Overlapping morphologic features may present a diagnostic challenge to the surgical pathologist. Similarity in immunohistochemical profiles, often due to common cell type, as well as rare non-neoplastic mimics, furthers the diagnostic conundrum.

CONCLUSIONS

The top ten lesions reviewed in this article are as follows: (1) clear cell carcinoma (salivary and odontogenic), (2) mucoepidermoid carcinoma, (3) myoepithelial and epithelial-myoepithelial carcinoma, (4) oncocytic salivary gland lesions, (5) squamous cell carcinoma, (6) parathyroid water clear cell adenoma, (7) metastatic renal cell carcinoma (especially in comparison to clear cell thyroid neoplasms), (8) sinonasal renal cell-like adenocarcinoma, (9) chordoma, and (10) rhinoscleroma.

Nuclear expression of NHERF1/EBP50 in Clear Cell Renal Cell Carcinoma

The Na/H exchange regulatory factor 1 or Ezrin-radixin-moesin-binding phosphoprotein 50 (NHERF1/EBP50) is an adaptor protein implicated in the stabilization of molecular complexes linking extracellular signals with the cytoskeleton machinery. NHERF1 expression at the cell cortex is associated with the maintenance of adherent junction integrity in polarized epithelia. The role of NHERF1 in cancer depends on its localization within the cell, acting, in most cases, as a tumor suppressor when localized at the cell membrane, and as an oncogene, when expressed in the cytoplasm or the nucleus of cancer cells. The distribution of NHERF1 in renal cell carcinoma (RCC) has not been yet investigated. In this study, NHERF1 expression was examined by immunohistochemistry in papillary and clear cell RCC. We observed membranous staining in papillary RCC, whereas NHERF1 expression was nuclear and membranous in clear cell RCC. In comparison, NHERF1 immunohistochemistry in clear cell carcinomas of the ovary showed mainly nuclear staining. Our finding of the specific NHERF1 nuclear expression in clear cell carcinomas may help to elucidate the molecular changes that regulate its nuclear accumulation and to better understand its role in this cell compartment.

Extreme winter weather: A force to be remembered in dermatopathology

It is important for the dermatopathologist to be adept in differentiating tissue artifacts from normal tissue variants and pathologies. Numerous tissue artifacts have been described to date; however, once we are familiar with the common artifacts that appear in our practice, we may not immediately recognize other confounders. For example, dermatopathologists in more temperate regions of the country may not be familiar with freezing artifact. In this case series, we present three common diagnoses in dermatopathology that were obscured by the extreme winter weather that severely impacted the Southern United States in February 2021 and discuss methods to prevent these artifacts.

Differential Diagnosis between Oral Metastasis of Renal Cell Carcinoma and Salivary Gland Cancer

Renal cell carcinoma, which has clear cells in 70% of cases, has a high frequency of hematogenous distant metastases to lung, bone, liver, and other areas. Metastatic cancer accounts for 1 to 3% of malignant tumors in the stomatognathic region, and the metastasis of renal cell carcinoma to the oral mucosal tissue, though extremely rare, does occur. In addition, clear cells have been observed in some salivary gland cancers in the oral cavity. Therefore, the differential diagnosis of metastatic renal cell carcinoma and salivary gland cancer is important. This review discusses the differential diagnosis between metastatic renal cell carcinoma and malignant tumors of the salivary gland.