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Context.--Mutations within the same signature transduction pathway are redundant and, therefore, most are mutually exclusive. Laboratory errors, however, may introduce unexpected coexisting mutations. Objective.--To validate coexisting mutations within epidermal growth factor receptor (EGFR), mitogen-activated protein kinase, and phosphatidylinositol 3-kinase pathways. Design.--In this retrospective study for quality assessment of next-generation sequencing in a clinical diagnostics setting, coexisting mutations within EGFR, KRAS, NRAS, BRAF, AKT1, and PIK3CA genes were examined in 1208 non-small cell lung cancers. Results.--EGFR mutations did not coexist with BRAF mutations, neither kinase-activated nor kinase-impaired mutations. There was a low but similar incidence (3.3%5.1%) of PIK3CA mutations in BRAF-, EGFR-, and KRAS-mutated lung cancers and a rare incidence of coexisting KRAS and EGFR mutations detected in 1 of 1208 lung cancers (0.08%) or 1 of 226 EGFR-mutated lung cancers (0.4%). Coexisting BRAF p.V600E mutation was observed in 3 of 4 AKT1 p.E17K-mutated lung cancers. Mutational profiling of DNA reisolated from subareas with the same or different histomorphology, using an alternative assay, confirmed that coexisting mutations might present within the same (whole or subclonal) population or different populations and clarified that the so-called coexisting activating KRAS and BRAF mutations originally reported in a specimen were indeed present in separate lung nodules submitted in the same block. Conclusions.--The results supported that EGFR and BRAF mutations are early driver mutations in lung cancers. Guidelines from official organizations to establish standard operating procedures are warranted to validate unexpected coexisting mutations and, if clinically indicated, to determine their presence in the same or different tumor populations. doi: 10.5858/arpa.2017-0495-OA, Several therapeutic agents have been approved by the US Food and Drug Administration in the United States for targeted therapy of metastatic non-small cell lung cancers (NSCLCs). (1) These include [...]

We report a case of a DICER1-associated EWSR1-rearranged malignant primitive neuroectodermal tumor (PNET) arising in a patient with DICER1 tumor predisposition syndrome. A 16-yr-old female with a history of multinodular goiter presented with a widely met-astaticabdominal small round blue cell tumorwith neuroectodermal differentiation. EWSR1 gene rearrangement was identified in the tumor by fluorescence in situ hybridization (FISH). Genetic analysis revealed biallelic pathogenic DICER1 variation. The patient was treated with an aggressive course of chemotherapy, surgery, and radiation with complete pathologic response. We believe this case to represent a new expression of the DICER1 tumor predisposition syndrome, an entity caused by deleterious germline mutations in the DICER1 gene, encoding a ribonuclease active in the processing of miRNA. Patients with germline mutations in DICER1 develop a diverse group of benign and malignant tumors. Some of these tumors have been noted to have immature neuroepithelium as a component, including the ciliary body medulloepithelioma and the recently described DICERI-associated presacral malignant teratoid neoplasm. To our knowledge, abdominal sarcomas that resemble PNET histology with an EWSR1 rearrangement have not previously been described as a classical expression of the DICER1 syndrome phenotype. [ABSTRACT FROM AUTHOR]

Background: Selective IDH1 and IDH2 inhibitors have been approved for targeted therapy of acute myeloid leukemia. Clinical trials for solid tumors with IDH1 and IDH2 (IDH1/2) mutations are ongoing. Reports of IDH1/2‐mutated non–small cell lung cancers (NSCLCs), however, are limited. Methods: We evaluated IDH1/2 mutations in 1,924 NSCLC specimens (92% adenocarcinoma) using a next‐generation sequencing assay. Results: Retrospective quality assessments identified false detection of IDH1 c.395G>A (p.R132H) resulting from cytosine deamination (C:G→T:A) artifact in one specimen. IDH1/2 mutations were detected in 9 (0.5%) adenocarcinomas taken by fine‐needle aspiration (n = 3), thoracentesis (n = 2) or core biopsy (n = 4). All nine adenocarcinomas showed high‐grade features. Extensive clear cell change, however, was not observed. High expression (50% or greater) of PD‐L1 was observed in two of five specimens examined. IDH1/2 mutations were associated with old age, smoking history, and coexisting KRAS mutation. Lower than expected variant allele frequency of IDH1/2 mutants and coexistence of IDH1/2 mutations with known trunk drivers in the BRAF, EGFR, and KRAS genes suggest they could be branching drivers leading to subclonal evolution in lung adenocarcinomas. Multiregional analysis of an adenocarcinoma harboring two IDH2 mutations revealed parallel evolution originating from a KRAS‐mutated lineage, further supporting subclonal evolution promoted by IDH1/2 mutations. Conclusions: IDH1/2 mutations in NSCLCs are uncommon. They occur in adenocarcinomas with high‐grade features and may be branching drivers leading to subclonal evolution. Accumulation of more IDH1/2‐mutated NSCLCs is needed to clarify their clinicopathological characteristics and implications for targeted therapy. [ABSTRACT FROM AUTHOR]

* Context.--Spontaneous pneumothorax can be idiopathic (primary), or it can occur in association with an underlying predisposing condition (secondary). Spontaneous pneumothorax may be a harbinger of an undiagnosed clinical condition, which may be associated with serious systemic abnormalities, making early recognition and diagnosis important. The pulmonary pathology of some of these disorders has not been fully elucidated. Objective.--To review cases of pneumothorax in the hope of identifying pathologic features that might correlate to specific clinical syndromes. Design.--The pathology computer files at 3 hospitals were searched for all cases of spontaneous pneumothorax, primary and secondary, regardless of etiology during a 11year period. Ninety-two cases were retrieved. Each of the cases was evaluated for reactive eosinophilic pleuritis, elastosis, pleural fibrosis, emphysema, intra-alveolar macrophages, cholesterol clefts, vasculopathy, and intraparenchymal or intrapleural cysts. Clinical information regarding asthma and smoking history, site of the pneumothorax, family history, radiographic findings, predisposing conditions, recurrence, age, and sex were extracted from the medical records. Results.--In 11 patients (12% of all the patients with spontaneous pneumothorax), a distinctive pattern of pleural fibrosis with islands of fibroblastic foci within a myxoid stroma was noted at the pleural-parenchymal interface or leading edge. These lesions correlated with a select subset of patients, consisting predominantly of young men. Conclusions.--Our review identified a distinct pattern of pneumothorax-associated fibroblastic lesions in a subset of cases of spontaneous pneumothorax. Whether this is related to the pathogenesis of the pneumothorax remains to be elucidated. (Arch Pathol Lab Med. 2012; 136:1522-1527; doi: 10.5858/arpa.2012-0330-OA), Spontaneous pneumothorax (SP) is a well-recognized pulmonary complication of a wide variety of disorders, ranging from endometriosis to metastatic malignancy. It has been separated into primary and secondary types, where [...]

Objectives: To propose an operating procedure for validation of discordant trunk driver mutations.Methods: Concordance of trunk drivers was examined by next-generation sequencing in 15 patients with two to three metastatic lung cancers and 32 paired primary and metastatic lung cancers.Results: Tissue identity was confirmed by genotyping 17 single-nucleotide polymorphisms within the panel. All except three pairs showed concordant trunk drivers. Quality assessment conducted in three primary and metastatic pairs with discordant trunk drivers indicates metastasis from a synchronous or remote lung primary in two patients. Review of literature revealed high discordant rates of EGFR and KRAS mutations, especially when Sanger sequencing was applied to examine primary and lymph node metastatic tumors.Conclusions: Trunk driver mutations are highly concordant in primary and metastatic tumors. Discordance of trunk drivers, once confirmed, may suggest a second primary cancer. Guidelines are recommended to establish standard operating procedures for validation of discordant trunk drivers. [ABSTRACT FROM AUTHOR]

* Vibrio vulnificus is an extremely invasive gram-negative bacillus found in marine waters that causes overwhelming bacteremia and shock that is associated with high mortality. Impaired iron metabolism has been implicated in the susceptibility to V vulnificus bacterial infections. We report a case of fatal V vulnificus sepsis in a 56-year-old man who died within 1 to 3 days after consuming raw seafood. At autopsy, he was found to have micronodular cirrhosis and iron overload. Postmortem genetic analysis revealed the presence of the hemochromatosis gene (HFE) C282Y mutation. To our knowledge, this is this first documented fatal case of V vulnificus infection in a patient proven to carry the HFE C282Y mutation. Because this patient was heterozygous for the major hereditary hemochromatosis mutation and was not previously diagnosed with clinical iron overload, the spectrum of clinical susceptibilities to V vulnificus infection may include carriers of the C282Y mutation. (Arch Pathol Lab Med. 2001;125:1107-1109), Vibrio vulnificus is a halophilic noncholera Vibrio species that is a common microbe in seawater and may cause gastroenteritis and wound infections.[1] Primary septicemia can occur in patients who have [...]

The development of cystic fibrosis transmembrane conductance regulator (CFTR) targeted therapy for cystic fibrosis has generated interest in maximizing membrane residence of mutant forms of CFTR by manipulating interactions with scaffold proteins, such as sodium/hydrogen exchange regulatory factor-1 (NHERF1). In this study, we explored whether COOH-terminal sequences in CFTR beyond the PDZ-binding motif influence its interaction with NHERF1. NHERF1 displayed minimal self-association in blot overlays (NHERF1, Kd = 1,382 ± 61.1 nM) at concentrations well above physiological levels, estimated at 240 nM from RNA-sequencing and 260 nM by liquid chromatography tandem mass spectrometry in sweat gland, a key site of CFTR function in vivo. However, NHERF1 oligomerized at considerably lower concentrations (10 nM) in the presence of the last 111 amino acids of CFTR (20 nM) in blot overlays and cross-linking assays and in coimmunoprecipitations using differently tagged versions of NHERF1. Deletion and alanine mutagenesis revealed that a six-amino acid sequence 1417EENKVR1422 and the terminal 1478TRL1480 (PDZ-binding motif) in the COOH-terminus were essential for the enhanced oligomerization of NHERF1. Full-length CFTR stably expressed in Madin-Darby canine kidney epithelial cells fostered NHERF1 oligomerization that was substantially reduced (∼5-fold) on alanine substitution of EEN, KVR, or EENKVR residues or deletion of the TRL motif. Confocal fluorescent microscopy revealed that the EENKVR and TRL sequences contribute to preferential localization of CFTR to the apical membrane. Together, these results indicate that COOH-terminal sequences mediate enhanced NHERF1 interaction and facilitate the localization of CFTR, a property that could be manipulated to stabilize mutant forms of CFTR at the apical surface to maximize the effect of CFTR-targeted therapeutics. [ABSTRACT FROM AUTHOR]

Background Mycobacterium tuberculosis (Mtb) must adapt to various stress conditions during host infection. The two-component regulatory system (2CRS) SenX3-RegX3 is required for Mtb virulence. We showed recently that the senX3-regX3 intergenic region contains promoter activity, driving senX3-independent regX3 expression. In the current study, we tested the hypothesis that RegX3 has a SenX3-independent role in Mtb virulence. The gene expression patterns, growth, and survival of mutants containing transposon insertions in senX3 (senX3::Tn) and regX3 (regX3::Tn) were compared to those of their respective complemented strains and the isogenic wild-type parent strain during axenic growth in nutrient-rich broth, phosphate depletion, nutrient starvation, and in the lungs of BALB/c mice. Results regX3 expression was reduced in senX3::Tn during phosphate depletion and nutrient starvation, and expression of the phosphate-specific transport gene pstC2 was reduced similarly in senX3::Tn and regX3::Tn during phosphate depletion. Although senX3 and regX3 were each dispensable for Mtb growth in nutrient-rich broth, disruption of senX3 or regX3 caused a similar growth defect during phosphate depletion. Interestingly, senX3::Tn, in which monocistronic regX3 expression is preserved, showed significantly higher survival relative to regX3::Tn after 7 days of nutrient starvation (p <0.01), and in mouse lungs at Day 31 (p < 0.01), Day 62 (p < 0.01), and Day 124 (p = 0.05) after aerosol infection. Conclusion Our data demonstrate the specificity of the senX3-regX3 2CRS for sensing and responding to low ambient phosphate, but also raise the possibility that RegX3 may function independently of its cognate sensor histidine kinase. [ABSTRACT FROM AUTHOR]

Abstract: Extralobar sequestration is a type of bronchopulmonary foregut malformation defined as an isolated portion of lung tissue with a systemic arterial supply, its own pleural investment, and no bronchial communication. While it may be recognized in utero or in the neonatal period, depending on its location and associated anomalies, it can also go unrecognized until later in life when it may present as a mass. We report the first case of adenocarcinoma arising in an extralobar sequestration. The patient was a 70-year old man with a 55 pack year smoking history who presented with chest discomfort and was found to have a 6.5cm right lower lobe mass. Percutaneous biopsy of the mass was positive for adenocarcinoma. At surgery, the mass was noted to have a separate arterial connection, no bronchial communication, and its own pleural investment, consistent with an extralobar sequestration. Malignancy arising in pulmonary sequestrations is rare and the few reported cases have been in intralobar types. Carcinoma arising in this setting adds to the dilemma of whether or not these developmental anomalies should be excised or followed. Our tumor, while small, did have vascular invasion. [Copyright &y& Elsevier]

Abstract: Spontaneous pneumothorax (SP) affects only a subset of patients in a variety of disorders. This multi-institutional study attempted to identify unique clinicopathologic features of spontaneous pneumothorax (SP) in a large cohort. A total of 111 cases from 109 patients were retrieved from 3 institutions over an 11-year period: 27 women, 82 men. 66 were smokers, 16 were non-smokers, 27 unknown. Sixty-six cases (61%) had identifiable disorders (secondary SP). Seven patients had a family history of lung disease: 2 of pneumothorax, 2 of lung cancer, and 1 each of emphysema, COPD, and not further classified. Forty-three cases (32 men, 11 women) were primary. The average age was 28 (men) and 37 (women). 17 smoked, 14 were non-smokers, and 12 unknown. In 26%, a unique recently described entity, pneumothorax-associated fibroblastic lesion (PAFL), was noted. 16% of this subset also had cellular alveolar septae. Abundant intraalveolar macrophages were noted in 12 cases. Five cases of unknown etiology had extensive bullous lung disease not otherwise classified. One patient had unusual cellular areas suggestive of LAM but negative for HMB-45. In conclusion, several distinct morphologic lesions were identified: PAFL, a subset with cellular septae, and a third with numerous intraalveolar macrophages. [Copyright &y& Elsevier]

The retinoblastoma (RB) tumor suppressor is believed to play an important role in the pathogenesis of osteosarcomas. Loss of function of RB may occur through abrogation of the RB/p16/cyclin D1 regularity pathway. Our study evaluated the protein expression of pRB, p16, and cyclin D1 in osteosarcomas: 27 tumor specimens from 20 patients were immunostained with antibodies to pRB, p16, and cyclin D1 using the avidin-biotin method with antigen retrieval. In a subset of cases, the immunohistochemical expression of pRB was correlated with loss of heterozygosity (LOH) at the RB locus; 56% of the specimens (15/27 cases) had an altered component of the pRB/p16/cyclin D1 pathway with pRB the most frequent abnormal protein (9/27 or 33%) and p16 and cyclin D1 immunohistochemically abnormal in 2 and 3 patients, respectively. Only one protein in the pathway was abnormally expressed in any individual specimen. Absent pRB expression was associated with LOH in 7 of 15 cases (47%), while in another 8 cases pRB was expressed immunohistochemically despite LOH noted by molecular analysis. Two cases were heterozygous by molecular analysis and demonstrated positive nuclear staining. These results support the role of the RB cell cycle control pathway (pRB, p16, cyclin D1) in the pathogenesis of a subset of osteosarcomas. The results also seem to identify a subset of osteosarcomas (about one-third in our study) in which other genetic factors, including others in this pathway, may be important. [ABSTRACT FROM AUTHOR]

Basal cell carcinoma is the most common of the cutaneous malignancies, accounting for 65 to 75% of all skin cancers. The natural history of this disease is one of chronic local invasion. Metastatic basal cell carcinoma is a rare clinical entity, with a reported incidence of only 0.0028 to 0.5%. Approximately 85% of all metastatic basal cell carcinomas arise in the head and neck region. We present a case of basal cell carcinoma that spread to the parotid gland in a man who had multiple lesions on his scalp and face. We also review the literature on metastatic basal cell carcinoma of the head and neck, and we discuss its epidemiology, etiology, histopathology, and treatment. [ABSTRACT FROM AUTHOR]

Context.--: Urinary and Male Genital Tumours is the 8th volume of the World Health Organization Classification of Tumours series, 5th edition. Released in hard copy in September 2022, it presents an update to the classification of male genital and urinary tumors in the molecular age. Building upon previous volumes in this series, significant effort has been made to harmonize terminology across organ systems for biologically similar tumors (eg, neuroendocrine tumors). Genomic terminology has been standardized and genetic syndromes covered more comprehensively. This review presents a concise summary of this volume, highlighting new entities, notable modifications relative to the 4th edition, and elements of relevance to routine clinical practice. Objective.--: To provide a comprehensive update on the World Health Organization classification of urinary and male genital tumors, highlighting updated diagnostic criteria and terminology. Data sources.--: The 4th and 5th editions of the World Health Organization Classification of Tumours: Urinary and Male Genital Tumours. Conclusions.--: The World Health Organization has made several changes in the 5th edition of the update on urinary and male genital tumors that pathologists need to be aware of for up-to-date clinical practice. [ABSTRACT FROM AUTHOR]

Introduces articles featured in the September 2000 issue of 'Pediatric Pathology and Molecular Medicine,' which looked at issues confronting practitioners in the study and treatment of osteosarcoma. Guidelines to distinguish osteosarcoma from osteoblastoma; Use of fine needle aspiration in diagnosis; Interobserver variability in diagnosis; Cytogenic and molecular features of osteosarcomas.

Analysis of lung adenocarcinomas for actionable mutations has become standard of care. Here, we report our experience using next generation sequencing (NGS) to examine AKT1 , BRAF , EGFR , ERBB2 , KRAS , NRAS , and PIK3CA genes in 1006 non-small cell lung cancers in a clinical diagnostic setting. NGS demonstrated high sensitivity. Among 760 mutations detected, the variant allele frequency (VAF) was 2-5% in 33 (4.3%) mutations and 2-10% in 101 (13%) mutations. A single bioinformatics pipeline using Torrent Variant Caller, however, missed a variety of EGFR mutations. Mutations were detected in KRAS (36% of tumors), EGFR (19%) including 8 (0.8%) within the extracellular domain (4 at codons 108 and 4 at codon 289), BRAF (6.3%), and PIK3CA (3.7%). With a broader reportable range, exon 19 deletion and p.L858R accounted for only 36% and 26% of EGFR mutations and p.V600E accounted for only 24% of BRAF mutations. NGS provided accurate sequencing of complex mutations seen in 19% of EGFR exon 19 deletion mutations. Doublet (compound) EGFR mutations were observed in 29 (16%) of 187 EGFR -mutated tumors, including 69% with two non-p.L858R missense mutations and 24% with p.L858 and non-p.L858R missense mutations. Concordant VAFs suggests doublet EGFR mutations were present in a dominant clone and cooperated in oncogenesis. Mutants with predicted impaired kinase, observed in 25% of BRAF -mutated tumors, were associated with a higher incidence of concomitant activating KRAS mutations. NGS demonstrates high analytic sensitivity, broad reportable range, quantitative VAF measurement, single molecule sequencing to resolve complex deletion mutations, and simultaneous detection of concomitant mutations., Competing Interests: CONFLICTS OF INTEREST The authors declare no conflicts of interest.

EGFR-mutated lung adenocarcinomas routinely develop resistance to tyrosine kinase inhibitors (TKI). To better characterize the relative frequencies of the resistance mechanisms, we analyzed 48 EGFR-mutated TKI-resistant specimens from 41 patients. Next-generation sequencing of post-treatment specimens detected EGFR p.T790M in 31 (79%) of 39 patients, PIK3CA mutations in 10 (26%), EGFR p.S768&#95;V769delinsIL in one, and KRAS p.G12C in one. Five PIK3CA mutations were outside of codons 542, 545, and 1047. Three of four pre-treatment specimens did not carry the PIK3CA mutation found in the post-treatment sample. Small cell carcinoma transformation was identified in four patients; none had p.T790M, including two where p.T790M was identified in the co-existing adenocarcinoma. In p.T790M-mutated specimens, the allele frequency was less than 5% in 24% of cases. p.T790M allele frequency was usually lower than that of the sensitizing mutation indicating that the resistance mutation was present either in a subset of cells or, if the sensitizing mutation was amplified, in a subset of the sensitizing alleles of a dominant clone. Eight patients had multiple resistance mutations, suggesting either multiple separate resistant clones or a single clone harboring multiple resistance mechanisms. PIK3CA mutations appear to be a more significant resistance mechanism than previously recognized., Competing Interests: The authors declare no conflicts of interest.

Elevated sweat chloride levels, failure to thrive (FTT), and lung disease are characteristic features of cystic fibrosis (CF, OMIM #219700). Here we describe variants in CA12 encoding carbonic anhydrase XII in two pedigrees exhibiting CF-like phenotypes. Exome sequencing of a white American adult diagnosed with CF due to elevated sweat chloride, recurrent hyponatremia, infantile FTT and lung disease identified deleterious variants in each CA12 gene: c.908-1 G>A in a splice acceptor and a novel frameshift insertion c.859&#95;860insACCT. In an unrelated consanguineous Omani family, two children with elevated sweat chloride, infantile FTT, and recurrent hyponatremia were homozygous for a novel missense variant (p.His121Gln). Deleterious CFTR variants were absent in both pedigrees. CA XII protein was localized apically in human bronchiolar epithelia and basolaterally in the reabsorptive duct of human sweat glands. Respiratory epithelial cell RNA from the adult proband revealed only aberrant CA12 transcripts and in vitro analysis showed greatly reduced CA XII protein. Studies of ion transport across respiratory epithelial cells in vivo and in culture revealed intact CFTR-mediated chloride transport in the adult proband. CA XII protein bearing either p.His121Gln or a previously identified p.Glu143Lys missense variant localized to the basolateral membranes of polarized Madin-Darby canine kidney (MDCK) cells, but enzyme activity was severely diminished when assayed at physiologic concentrations of extracellular chloride. Our findings indicate that loss of CA XII function should be considered in individuals without CFTR mutations who exhibit CF-like features in the sweat gland and lung., (© The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Strategies involving new drug combinations, as well as new uses of existing drugs, are urgently needed to reduce the time required to cure patients with drug-sensitive or multidrug-resistant (MDR) tuberculosis (TB). We compared the sterilizing activity of the standard first-line antitubercular regimen, rifampin-isoniazid-pyrazinamide (RHZ), with that of the novel regimen PA-824-moxifloxacin-pyrazinamide (PaMZ), which is currently being studied in clinical trials (NCT01498419), in the guinea pig model of chronic TB infection, in which animals develop necrotic granulomas histologically resembling their human counterparts. Guinea pigs were aerosol infected with ~2 log10 bacilli of wild-type Mycobacterium tuberculosis H37Rv, and antibiotic treatment was initiated 6 weeks after infection. Separate groups of animals received RHZ, PaMZ, or single or two-drug components of the latter regimen administered at human-equivalent doses 5 days/week for a total of 8 weeks. Relapse rates were assessed 3 months after discontinuation of treatment to determine the sterilizing activity of each combination regimen. PaMZ given at human-equivalent doses was safe and well tolerated for the entire treatment period and rendered guinea pig lungs culture negative more rapidly than RHZ did. After 1 month of treatment, 80% and 50% of animals in the RHZ and PaMZ groups, respectively, had lung culture-positive relapse. Both combination regimens prevented microbiological relapse when administered for a total of 2 months. Our data support the use of PaMZ as a novel isoniazid- and rifamycin-sparing regimen suitable for treatment of both drug-sensitive TB and MDR-TB.

The Mycobacterium tuberculosis gene Rv3232c/MT3329 (ppk2) encodes a class II polyphosphate kinase, which hydrolyzes inorganic polyphosphate (poly P) to synthesize GTP. We assessed the role of ppk2 in M. tuberculosis poly P regulation, antibiotic tolerance, and virulence. A ppk2-deficient mutant (ppk2::Tn) and its isogenic wild-type (WT) and complemented (Comp) strains were studied. For each strain, the intrabacillary poly P content, MIC of isoniazid, and growth kinetics during infection of J774 macrophages were determined. Multiplex immunobead assays were used to evaluate cytokines elaborated during macrophage infection. The requirement of ppk2 for M. tuberculosis virulence was assessed in the murine model. The ppk2::Tn mutant was found to have significantly increased poly P content and a 4-fold increase in the MIC of isoniazid relative to the WT and Comp strains. The ppk2::Tn mutant showed reduced survival at day 7 in activated and naive J774 macrophages relative to the WT. Naive ppk2::Tn mutant-infected macrophages showed increased expression of interleukin 2 (IL-2), IL-9, IL-10, IL-12p70, and gamma interferon (IFN-γ) relative to WT-infected macrophages. The ppk2::Tn mutant exhibited significantly lower lung CFU during acute murine infection compared to the control groups. ppk2 is required for control of intrabacillary poly P levels and optimal M. tuberculosis growth and survival in macrophages and mouse lungs. IMPORTANCE Mycobacterium tuberculosis, the causative agent of tuberculosis (TB), is a highly successful human pathogen because it has developed mechanisms to multiply and survive in the lungs by circumventing the immune system. Identification of virulence factors responsible for M. tuberculosis growth and persistence in host tissues may assist in the development of novel strategies to treat TB. In this study, we found that the mycobacterial enzyme polyphosphate kinase 2 (PPK2) is required for controlling intracellular levels of important regulatory molecules and for maintaining susceptibility to the first-line anti-TB drug isoniazid. In addition, PPK2 was found to be required for M. tuberculosis growth in the lungs of mice, at least in part by suppressing the expression of certain key cytokines and chemokines by inactivated lung macrophages.