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We report an unusual case of recurrent encephalopathy due to acquired hemophagocytic lymphohistiocytosis (HLH) in a patient with propionic acidemia (PA). PA is an inherited metabolic disorder in which patients often present with encephalopathy and pancytopenia during metabolic decompensation. However, these patients may rarely develop HLH with similar presentation. This case illustrates the need to distinguish HLH induced encephalopathy from the one secondary to metabolic decompensation in these patients, as early diagnosis and treatment of HLH improves prognosis. This case also highlights the importance of considering HLH in patients presenting with unexplained encephalopathy, as early diagnosis and treatment is lifesaving in this otherwise lethal condition. To our knowledge this is the first case report of acquired HLH presenting as recurrent encephalopathy followed by complete recovery, in a metabolically stable patient with PA.

Antibody to renal cell carcinoma (RCC) antigen, a normal human proximal brush border antigen, has recently become commercially available and reported to be highly specific and a relatively sensitive marker for RCC. Of the nonrenal tumors occasional carcinomas have been reported to express RCC, notably breast carcinoma. Using tissue microarrays, we investigated the use of RCC on a large number of renal epithelial neoplasms (RENs) and nonrenal tumors, especially those potentially confused with REN. Three tissue microarrays containing 241 REN samples, 192 samples of a wide variety of neoplasms and 170 adrenal tumor samples, respectively, were stained with RCC monoclonal antibody. RCC expression was scored for staining intensity and percentage expression. Out of 241 REN, 173 were positive for RCC (sensitivity 72%): clear cell 72%, papillary 95%, chromophobe 91%, unclassified 85%, oncocytoma 75%, sarcomatoid 20%, and metastatic RCC 40%. The overall immunostaining intensity was consistently much higher in papillary and clear cell RCC than in other tumors. Seventy-six out of 362 nonrenal tumor samples demonstrated either focal or diffuse expression for RCC (specificity 79%). These included: adrenocortical neoplasms 37/170 (22%), colonic 11/29 (37.5%), breast 9/27 (33%), prostate 5/18 (27.7%), ovary 2/17 (11.7%), melanoma 3/18 (16.6%), lung 3/21 (14.2%), and parathyroid 3/3 (100%). RCC expression was seen equally among adrenal adenoma and carcinoma group. Eight out of 28 (28.5%) normal adrenal cores also stained for RCC. RCC is a relatively useful marker in the differential diagnosis of REN only if used in a panel with other positive and negative markers. RCC does not reliably differentiate REN, especially classic clear cell type, from adrenocortical neoplasms, which are frequently confused due to close anatomic proximity and similar morphology. RCC also does not reliably differentiate subtypes of renal epithelial neoplasms.

Context.—Fascin is an actin-bundling protein involved in the formation of dendritic processes. Fascin is a sensitive marker for classical Reed-Sternberg cells and has a high negative predictive value for diagnosis of classical Hodgkin lymphoma (CHL). Fascin has been used to distinguish CHL from non-Hodgkin lymphoma. Recently, it was shown that fascin might not help differentiate CHL from anaplastic large cell lymphoma (ALCL). Moreover, fascin has not been extensively studied in the context of other large cell lymphomas. Objective.—To analyze fascin expression in diffuse large B-cell lymphoma (DLBCL) and also reexamine its usefulness in discriminating CHL from ALCL. Design.—Formalin-fixed, paraffin-embedded tissue samples from 41 cases of DLBCL, 30 cases of CHL, and 30 cases of ALCL were analyzed. Fascin expression was compared across each type of lymphoma with additional correlation between fascin positivity and ALK-1 expression in ALCL performed. Results.—Only 6 (14.6%) of 41 cases of DLBCL stained positively for fascin, with most neoplastic large cells exhibiting a weak staining pattern. Fifteen (50%) of 30 cases of ALCL showed positivity for fascin, with most large cells staining strongly. All 30 cases of CHL demonstrated intense positive staining. Sixty percent of fascin-positive ALCLs were positive for ALK-1, while 66.7% of fascin-negative ALCLs were positive for ALK-1. Conclusions.—Fascin is highly sensitive for CHL and has a very high negative predictive value (100% in this series) for distinguishing CHL from DLBCL or ALCL. However, the specificity and positive predictive value for fascin are much higher in distinguishing CHL from DLBCL than in distinguishing CHL from ALCL. Expression of fascin appears more useful in the differential diagnosis of CHL versus DLBCL than in the differential diagnosis of CHL versus ALCL.

We describe the clinical, radiologic, and pathologic features of primary bone anaplastic large cell lymphoma (ALCL) in 3 boys. Radiologic imaging showed lytic lesions involving sacrum, femur, or rib. Bone was the only site of disease in 2 cases; an associated partial lymph node was involved in case 3. Differential diagnoses included osteomyelitis and small round cell tumors of childhood, particularly Ewing sarcoma. Preoperatively, ALCL was not a diagnostic consideration in any case. Two cases showed classic large pleomorphic cells; 1 showed a composite pattern with a distinct small cell component and the more typical large cell type. Neoplastic cells in all cases showed strong CD30 and anaplastic lymphoma kinase expression with relatively weak epithelial membrane antigen positivity. Cytotoxic granule protein was expressed in 2 cases. All cases showed unusually strong expression of neuron-specific enolase (NSE). Two patients were disease-free at last follow-up (15 months and 11 years); 1 patient died of disseminated disease within a year of diagnosis. ALCL should be considered a diagnostic possibility when evaluating neoplastic bone lesions in children. Although expression of NSE in ALCL has not been emphasized in the literature, it is worth noting because it may pose a diagnostic pitfall.

BACKGROUND: The usefulness of fine needle aspiration cytology (FNAC) in the diagnosis of lung lesions is well documented. Fungal lesions are among nonneoplastic lesions of the lung in which FNAC has proven a useful technique in both immunocompromised and immunocompetent patients. These include cryptococcosis, aspergillosis, histoplasmosis and coccidiodomycosis. Pulmonary mucormycosis, an aggressive fungal infection, is rarely diagnosed on FNAC. We report a case of isolated pulmonary mucormycosis diagnosed on FNAC. CASE: A 62-year-old renal transplant recipient with diabetes mellitus and hypertension, asymptomatic for four months, presented with tachypnea, generalized malaise and weakness. Radiologic studies showed an enlarging, cavitating lesion in the right lung. Computed tomography-guided fine needle aspiration performed on the lung lesion showed fungal profiles with broad, ribbonlike, aseptate hyphae with right-angled branching consistent with the Zygomycetes class of fungi, which includes Rhizopus and Mucor species. Fungal cultures confirmed the presence of Rhizopus. The patient underwent right pneumonectomy, was placed on liposomal amphotericin B therapy and discharged with good pulmonary status and stable kidney function, CONCLUSION: FNAC is a useful technique in the diagnosis of pulmonary mucormycosis.

Distinctive dermal clear cell mesenchymal neoplasm (DDCCMN) is a newly described entity characterized by a dermal proliferation of neoplastic cells with clear to reticulated cytoplasm and vesicular nuclei. Atypical features in the form of nuclear pleomorphism and mitoses may be found. The histogenesis of these neoplastic clear cells is not currently known but they are thought to be mesenchymal in origin. Immunohistochemically, they stain positively for NKI-C3 and negatively for melanocytic, epithelial and lymphoid markers. All five cases originally reported by Lazar and Fletcher occurred in the lower extremities. We report herein a case of DDCCMN with atypical features arising in the scalp.

We describe the clinical, radiologic, and pathologic features of primary bone anaplastic large cell lymphoma (ALCL) in 3 boys. Radiologic imaging showed lytic lesions involving sacrum, femur, or rib. Bone was the only site of disease in 2 cases; an associated partial lymph node was involved in case 3. Differential diagnoses included osteomyelitis and small round cell tumors of childhood, particularly Ewing sarcoma. Preoperatively, ALCL was not a diagnostic consideration in any case. Two cases showed classic large pleomorphic cells; 1 showed a composite pattern with a distinct small cell component and the more typical large cell type. Neoplastic cells in all cases showed strong CD30 and anaplastic lymphoma kinase expression with relatively weak epithelial membrane antigen positivity. Cytotoxic granule protein was expressed in 2 cases. All cases showed unusually strong expression of neuron-specific enolase (NSE). Two patients were disease-free at last follow-up (15 months and 11 years); 1 patient died of disseminated disease within a year of diagnosis. ALCL should be considered a diagnostic possibility when evaluating neoplastic bone lesions in children. Although expression of NSE in ALCL has not been emphasized in the literature, it is worth noting because it may pose a diagnostic pitfall.

With increasing sophistication of imaging modalities, many small indeterminate renal masses are detected, posing therapeutic dilemmas. Minimally invasive techniques such as radio frequency ablation (RFA) and cryotherapy are increasingly used in such settings, making it essential to classify renal mass in biopsies. We evaluated indications, adequacy, spectrum, and limitations of pathological diagnoses in 52 (79%) of 66 adequate biopsies that impacted management by having conservative therapy (less than total nephrectomy). Indication for biopsies in this group was exclusively for indeterminate mass. Biopsies were categorized as 52% clear cell renal cell carcinoma (RCC); 11% papillary RCC; 23% oncocytic neoplasms, subdivided as oncocytoma (10), chromophobe RCC (1), and cannot rule out RCC (1); 8% spindle cell neoplasms; 2% round blue cell tumors; and 4% inflammatory. After biopsy, 29% underwent nephron-sparing surgery, 36% underwent RFA, and 35% were followed up with observation only. One (2%) unresolved oncocytic neoplasm proved to be a chromophobe RCC in the total nephrectomy. Of the 19 patients, 15 who underwent RFA after diagnostic biopsy subsequently underwent post-RFA biopsy to assess therapy response. Complete ablation at first attempt was achieved in 12 of 15 patients. In contemporary urological practice, biopsies are increasingly performed for incidentally detected renal mass to influence the clinical management. Most biopsies can be classified into clinically relevant categories; however, caution is advised while interpreting oncocytic neoplasms because sampling and tumor heterogeneity may adversely affect interpretation.